EPUK & IAQM u GUIDANCE
Planning For Air Quality
Land-Use Planning & Development Control:
Planning For Air Quality
www.iaqm.co.ukwww.environmental-protection.org.uk
Guidance from Environmental Protection UK and the Institute of Air Quality Management for the
consideration of air quality within the land-use planning and development control processes.
January 2017
EPUK & IAQM u GUIDANCE
Planning For Air Quality
2
Contents
EPUK & IAQM u GUIDANCE
Planning For Air Quality
Acknowledgements 3
Record of substantive amendments 4
1. Purpose and structure of this guidance 6
2. The Role of the Planning Regime 8
3. Links between poor air quality, human health and the environment 9
4. Planning Framework 11
Policy context 11
Supplementary Planning Documents and Guidance 12
The Planning Process 12
Material Considerations 12
Air quality as a material consideration 13
Linkages with other relevant issues 13
5. Better by design 14
Introduction 14
Overarching Concepts in Land Use Planning for Better Air Quality 14
Making Better Use of the Land-use Planning System 14
Examples of Approaches to Reducing Emissions and Impacts 16
Principles of Good Practice
17
Offsetting Emissions 18
6. Undertaking an Air Quality Assessment 19
Purpose 19
The need for an air quality assessment 19
Impacts of the Local Area on the Development 20
Impacts of the Development on the Local Area 21
Content of an air quality assessment 22
Agreement of datasets and methodologies 24
Describing the impacts 26
7. Assessing Significance 29
8. Mitigating Impacts 31
Abbreviations and acronyms 32
Table 4.1: Context of air quality and planning in England. 12
Table 6.1: Stage 1 Criteria 20
Table 6.2: Indicative criteria for requiring an air quality assessment 21
Table 6.3: Impact descriptors for individual receptors 25
Figure 1: Procedure for Evaluating New Developments 7
Figure 2: Role of Local Authority and Applicant/Developer in the planning process 15
Box 1: Examples of Approaches to Reducing Emissions and Impacts 14
EPUK & IAQM Land-Use Planning & Development Control: Planning For Air Quality 3
Acknowledgements
Disclaimer: This guidance was produced as a result of the
voluntary contribution of individuals within the Working
Group, who are members of EPUK and/or IAQM, for which
both organisations are grateful. Whilst this guidance represents
a consensus view of the Working Group, it does not necessarily
represent the view of individual members.
The information in this document is intended to provide
guidance for those working in land-use planning and
development control, and does not constitute legal advice.
The IAQM and EPUK have endeavoured to ensure that all
information in this document is accurate. However, neither
organisation will accept liability for any loss, damage or
inconvenience arising as a consequence of any use of or the
inability to use any information in this guidance. We are not
responsible for any claims brought by third parties arising from
your use of this Guidance.
Chairs of the Working Group
Stephen Moorcroft, Air Quality Consultants
Roger Barrowcliffe, Clear Air Thinking
Members of the Working Group
Paul Cartmell, Lancaster CC
Mark Chapman, Jacobs
Ben Coakley, Chiltern DC
Beth Conlan, Ricardo-AEA
Ana Grossinho, Air Quality Experts Global Ltd
Graham Harker, Peter Brett Associates
Claire Holman, Brook Cottage Consultants
Nigel Jenkins, Sussex AQ Partnership
Marilena Karyampa, Arup
Julie Kent, Rotherham MBC
Rachel Kent, Wiltshire DC
Duncan Laxen, Air Quality Consultants
Oliver Matthews, Carmarthenshire Council
Fiona Prismall, RPS Planning & Development
Rebecca Shorrock, Cheshire East Council
Claire Spendley, South Oxfordshire DC
Stuart Stearn
Alex Stewart, Public Health England
Adrian Young, Environment Agency
Environmental Protection UK: Environmental Protection UK
is a national charity that provides expert policy analysis and
advice on air quality, land quality, waste and noise and their
effects on people and communities in terms of a wide range of
issues including public health, planning, transport, energy and
climate. Membership of Environmental Protection UK is drawn
from local authorities, industry, consultancies and individuals
who are practicing professionals in their field, or have an interest
in the environment.
The Institute of Air Quality Management (IAQM): IAQM
aims to be the authoritative voice for air quality by maintaining,
enhancing and promoting the highest standards of working
practices in the field and for the professional development of
those who undertake this work. Membership of IAQM is mainly
drawn from practising air quality professionals working within
the fields of air quality science, air quality assessment and air
quality management.
Graphic Design: Darren Walker (darrengraphidesign.com)
Copyright statement: Copyright of these materials is held by
the members of the Working Group. We encourage the use of
the materials but request that acknowledgement of the source
is explicitly stated. All design rights are held by the IAQM, unless
otherwise stated.
Suggested citation: Moorcroft and Barrowcliffe. et al. (2017)
Land-use Planning & Development Control: Planning for Air
Quality. v1.2. Institute of Air Quality Management, London.
Contact: IAQM
c/o Institution of Environmental Sciences
3rd Floor, 140 London Wall, London
EC2Y 5DN
T: +44 (0)20 7601 1920
Date: January 2017
Cover image: © Stanko07 | Dreamstime.com
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Planning For Air Quality
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Planning For Air Quality
Record of substantive amendments
Original
location
Revised
location
Amendment made
Throughout
--- Reference to LAQM TG (09) updated to reflect the Technical Guidance issued in 2016
Throughout
--- Reference to the Environment Agency’s H1 methodology updated to reflect the withdrawal of this guidance
and its replacement in February 2016.
1.9 1.9 Replacement paragraph as follows: This guidance could be adapted for use in the Scottish and/or Northern
Ireland planning systems, because it is considered that the general principles of air quality assessment set
out herein are applicable in all parts of the United Kingdom.
3.4 3.4
Replacement final sentence: The Committee recommends that concentration response functions for the
association between NO
2
and premature mortality can be used, with some qualifications [footnote]. When
applied on a national basis, use of these functions suggests that the national premature mortality burden
for long term exposure to NO
2
is equivalent to 23,000 deaths annually [footnote].
New footnote: www.gov.uk/government/publications/nitrogen-dioxide-interim-view-on-long-term-
average-concentrations-and-mortality
New footnote: www.gov.uk/government/uploads/system/uploads/attachment_data/file/486636/aq-
plan-2015-overview-document.pdf
6.3 6.4 Additional paragraph: The guidance provided by the Environment Agency and Highways England has a
formal status, reflecting the connections these organisations have with Government departments. This
EPUK/IAQM guidance has no such status and is not intended as a substitute for the formal guidance.
6.8 6.9 Additional text: The use of a Simple Assessment may be appropriate, where it will clearly suffice for
the purposes of reaching a conclusion on the significance of effects on local air quality. The principle
underlying this guidance is that any assessment should provide enough evidence that will lead to a sound
conclusion on the presence, or otherwise, of a significant effect on local air quality. A Simple Assessment
will be appropriate, if it can provide this evidence Similarly, it may be possible to conduct a quantitative
assessment that does not require the use of a dispersion model run on a computer.
6.9 6.10 Amended text: The criteria provided are precautionary and should be treated as indicative. They are
intended to function as a sensitive ‘trigger’ for initiating an assessment in cases where there is a possibility
of significant effects arising on local air quality. This possibility will, self-evidently, not be realised in many
cases. The criteria should not be applied rigidly; in some instances, it may be appropriate to amend them
on the basis of professional judgement, bearing in mind that the objective is to identify situations where
there is a possibility of a significant effect on local air quality.
Additional text: In certain circumstances, it may be necessary to consider whether the site itself is suitable
for the introduction of new emission sources. This could be because the neighbouring land use has
particular sensitivities to increased exposure to air pollutants. It is not possible, or desirable, to set criteria
that would define such circumstances. In practice, it is more likely that an assessment would reach a
conclusion taking any local factors into account.
Original
location
Revised
location
Amendment made
Table 6.2;
row 7
Table 6.2;
row 7
‘kWh’ corrected to ‘kW’
v1.1. June 2015
v1.2. January 2017
EPUK & IAQM Land-Use Planning & Development Control: Planning For Air Quality 5
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Planning For Air Quality
Original
location
Revised
location
Amendment made
6.14 6.16 Additional text: The principle underlying this guidance is that any assessment should provide enough
evidence that will lead to a sound conclusion on the presence, or otherwise, of a significant effect on local
air quality. A Simple Assessment will be appropriate, if it can provide this evidence.
Table 6.2 Table 6.2 Rows 7 and 8 merged.
Replacement text in left hand column: Have one or more combustion processes, where there is a risk of
impacts at relevant receptors.
NB. this includes combustion plant associated with standby emergency generators (typically associated
with centralised energy centres) and shipping.
Replacement text in right hand column: Typically, any combustion plant where the single or combined
NOx emission rate is less than 5 mg/sec is unlikely to give rise to impacts, provided that the emissions are
released from a vent or stack in a location and at a height that provides adequate dispersion.
In situations where the emissions are released close to buildings with relevant receptors, or where the
dispersion of the plume may be adversely affected by the size and/or height of adjacent buildings (including
situations where the stack height is lower than the receptor) then consideration will need to be given to
potential impacts at much lower emission rates.
Conversely, where existing nitrogen dioxide concentrations are low, and where the dispersion conditions are
favourable, a much higher emission rate may be acceptable.
6.32 6.33 Additional text: Users of the impact descriptors set out in Table 6.3 are encouraged to follow the
explanatory notes carefully and recognise the spirit in which they apply. In particular, the intention is that
the descriptors should not be applied too rigidly and assessors should recognise the inevitable uncertainties
embedded within the process of their determination.
6.33 6.34 Replacement text: Most particulate matter from combustion processes (including road traffic) occurs in
the PM
2.5
fraction. The AQAL for PM
2.5
is lower than that for PM
10
, and this therefore represents the more
conservative approach for these sources. The application of Table 6.3 for PM
2.5
is straightforward, given
that the AQAL is expressed as an annual mean. In assessing road traffic sources, however, regard must also
be given to emissions from brake/tyre wear and road abrasion, which are predominantly in the 2.5-10
μm
fraction. Consequently, PM
10
is the more appropriate pollutant to assess in these circumstances. For the
assessment of PM
10
, Table 6.3 should be applied using an AQAL of 40 μg/m
3
as an annual mean; in addition,
consideration should also be given to the daily mean AQAL. This can be done using a derived value for the
annual mean based on the number of days exceeding a daily mean concentration of 50
μg/m
3
being no
more than 35 times per year. (The equation in LAQM.TG16 shows an annual mean of 32
μg/m
3
equating to 35
days at or above 50
μg/m
3
).
6.37 6.38 Deleted text: It is preferred that the annual mean AQAL is used for this pollutant.
6.38 6.39 Amended text: Where such peak short term concentrations from an elevated source are in the range 101-
20% of the relevant AQAL, then their magnitude can be described as small, those in the range 20
1-50%
medium and those above 50
1% as large.
7.7 7.8 Additional paragraph: The population exposure in many assessments will be evaluated by describing the
impacts at individual receptors. Often, these will be chosen to represent groups of residential properties,
for example, and the assessor will need to consider the approximate number of people exposed to impacts
in the various different categories of severity, in order to reach a conclusion on the significance of effect.
An individual property exposed to a moderately adverse impact might not be considered a significant
effect, but many hundreds of properties exposed to a slight adverse impact could be. Such judgements
will need to be made taking into account multiple factors and this guidance avoids the use of prescriptive
approaches.
7.12 7.13 Replacement text: Where the air quality is such that an air quality objective at the building façade is not
met, the effect on residents or occupants will be judged as significant, unless provision is made to reduce
their exposure by some means.
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1. Purpose and structure of this guidance
1.1 Environmental Protection UK (EPUK) and the Institute of Air
Quality Management (IAQM) have produced this guidance to
ensure that air quality is adequately considered in the land-use
planning and development control processes.
1.2
The spatial planning system has an important role to play in
improving air quality and reducing exposure to air pollution. Both
the development of local planning policies and the determination
of individual planning applications are important, the former
setting the framework for the latter. This guidance focuses
on development control, but also stresses the importance of
having good air quality policies within local authority planning
frameworks.
1.3 The intended audience for this guidance is made up of
air quality and planning officers within local authorities, and
developers and consultants involved in the preparation of
development proposals and planning applications.
1.4 This document has been developed for professionals operating
within the planning system. It provides them with a means of
reaching sound decisions, having regard to the air quality implications
of development proposals. It also is anticipated that developers
will be better able to understand what will make a proposal more
likely to succeed. This guidance, of itself, can have no formal or
legal status and is not intended to replace other guidance that does
have this status. For example, industrial development regulated by
the Environment Agency, and requiring an Environmental Permit, is
subject to the EA’s risk assessment methodology
1
, while for major
new road schemes, Highways England has prepared a series of
advice notes on assessing impacts and risk of non-compliance
with limit values
2
.
1.5
This guidance document is particularly applicable to assessing
the effect of changes in exposure of members of the public
resulting from residential and mixed-use developments, especially
those within urban areas where air quality is poorer. It will
also be relevant to any other forms of development where a
proposal could affect local air quality and for which no other
guidance exists. This guidance is not intended to be applied
to the assessment of air quality impacts on designated nature
conservation sites
3
.
1.6 The guidance sets out why air quality is an important
consideration in many aspects of local authority spatial planning.
It emphasises how good spatial planning can reduce exposure to air
pollution, as well as providing other benefits of well-being to the
wider community. It also emphasises the importance of applying
good design and ‘best-practice’
4
measures to all developments,
to reduce both pollutant emissions and human exposure. It also
provides guidance on how air quality considerations of individual
schemes may be considered within the development control
process, by suggesting a framework for the assessment of the
impacts of developments on local air quality.
1.7 Chapters 1 to 4 of this guidance set out the role of the planning
regime, the important links between air quality and human health,
and the links between planning and environmental assessment.
Chapters 5 to 8 then describe the roles of the local authority
and developer/applicant in the process through which air quality
and planning decisions are taken. More specifically, Chapter
5 deals with the overarching concepts of land-use planning
and air quality that should be applied throughout the strategic
planning and development control processes; it emphasises
that all developments should incorporate good principles of
design with regard to minimising emissions and the reduction
of impacts on local air quality. Chapters 6 to 8 then deal with
the assessment of individual planning applications; the approach
set out herein is founded on the concept that the principles
set out in Chapter 5 are firmly adhered to, but recognises that
within the development control process decisions have to be
made by local planning authorities on a case-by-case basis. A
flow chart describing the overall process through Chapters 5 to
8 is shown below in Figure 1.
1.8 This guidance is not intended to cover the specific assessment
of odour or construction dust effects that some developments
may give rise to. Separate guidance has been published by
IAQM i.e. ‘Guidance on the assessment of odour for planning’
and ‘Guidance on the assessment of dust from demolition and
construction’ and these guidance documents should be consulted
as appropriate
5
.
1.9
This guidance could be adapted for use in the Scottish and/
or Northern Ireland planning systems, because it is considered
that the general principles of air quality assessment set out herein
are applicable in all parts of the United Kingdom.
Figure 1: Procedure for Evaluating New Developments
EPUK & IAQM Land-Use Planning & Development Control: Planning For Air Quality 7
EPUK & IAQM u GUIDANCE
Planning For Air Quality
1. Review proposed development for evidence of
emission reduction and good design (See Chapter 5).
2. Screen where an air quality assessment
required (see Chapter 6)
3. Undertake an air quality assessment (See
Chapter 6).
4. Determine whether the air quality impact or
exposure is significant or not (see Chapter 7).
5. If significant identify additional mitigation
required.
6. Prepare air quality report.
2a. If not prepare short report/technical
note explaining the grounds for
screening out the need for an assessment.
1
https://www.gov.uk/guidance/air-emissions-risk-assessment-for-your-environmental-permit
2
www.standardsforhighways.co.uk/ians.
3
The IAQM and the Chartered Institute of Ecology and Environmental Management are considering (as of Spring 2015) where such guidance would be useful
for professionals working in this area.
4
Best practice in this guidance implies those measures which are currently considered to be the best available – this does not preclude better practice in the future.
5
http://iaqm.co.uk/guidance.
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2. The Role of the Planning Regime
2.1 Land-use planning can play a critical role in improving local
air quality. At the strategic level, spatial planning can provide for
more sustainable transport links between the home, workplace,
educational, retail and leisure facilities, and identify appropriate
locations for potentially polluting industrial development. For
an individual development proposal, there may be associated
emissions from transport or combustion processes providing
heat and power.
2.2 The pattern of land use determines the need for travel,
which is in turn a major influence on transport related emissions.
Decisions made on the allocation of land use will dictate future
emissions, as many people and businesses will make significant
use of road transport for journeys between places that form
part of their daily lives. Suppressing this demand for travel by
road can only be achieved by having a plan that recognises this
demand. Considering the merits of individual development
proposals in isolation is less likely to deliver a pattern of land
use that is more sustainable. Ideally, planning authorities should
have policies that reflect the desirability of reducing the demand
for road journeys with polluting vehicles. Local Transport Plans,
prepared in England by strategic transport authorities, contain
some of this thinking and are required to consider mechanisms
for reducing the need for travel.
2.3 Policies that promote high quality building standards,
reduce energy use, and require the preparation of low emissions
strategies, can help to reduce local emissions of air pollutants.
They will also align with other policies aimed at increasing
sustainability, notably for reducing greenhouse gas emissions.
2.4 Development is not inherently negative for air quality. Whilst
a new development at a particular site may have its own emissions,
it may also bring an opportunity to reduce overall emissions in
an area over time by installing new, cleaner technologies and
applying policies that promote sustainability. The installation of
more efficient low NO
x
boilers is one obvious example.
2.5 The National Planning Policy Framework (NPPF) in England,
and Planning Policy Wales (PPW), set out the important role
of local authorities as contributing to the protection of and
enhancement of the environment. As part of this role they should
help to improve biodiversity, minimise waste and pollution, and
mitigate and adapt to climate change including moving to a low
carbon economy. It requires local authorities to grant planning
permission in conformity with NPPF/PPW and the local plan,
where there are no relevant policies or where these are out of
date, unless any adverse impacts of doing so would significantly
and demonstrably outweigh the benefits.
2.6 Specifically, planning policies should sustain compliance
with, and contribute towards, meeting EU limit values or national
objectives for air pollutants
6
, taking into account the presence
of Air Quality Management Areas (AQMAs) and the cumulative
impacts on air quality from individual sites in local areas. Planning
decisions should ensure that any new development in an Air
Quality Management Area is consistent with the local air quality
action plan.
2.7 Local authorities therefore need to set out their policies to
achieve good air quality, both within Air Quality Management
Areas and more widely across their districts and periodically to
review them to keep them relevant and up to date.
2.8 Many authorities have already done so and have included
these in their air quality action plans, supplementary planning
documents or within other documents.
6
The air quality objectives for England are defined in the Air Quality (England) Regulations 2000 and the Air Quality (England) (Amendment) Regulations 2002;
within Wales they are defined in the Air Quality (Wales) Regulations 2000 and the Air Quality (Wales) (Amendment) Regulations 2002. The EU Limit Values are
transposed into UK legislation within the Air Quality Standards Regulations 2010.
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3.1 Planning has an important influence on air quality and also,
therefore, the health of humans and ecosystems. Ideally, air
quality should be a prime consideration for long term planning,
so that land is used and allocated in ways that minimise emissions
and that reduce the exposure of people to air pollution. As
a minimum, the planning system should not take decisions
on individual proposals that lead to unacceptably poor air
quality, nor should it make a series of decisions that collectively
produces this undesirable outcome. The best means of ensuring
that this does not occur is to have sound policies in place that
guide decision making. This document explains what those
desirable policies might be to promote better air quality and
how individual proposals are best evaluated.
3.2
It is now beyond dispute that air quality is a major influence
on public health and so improving air quality will deliver real
benefits. In England, with the move of Directors of Public Health
into local authorities, along with the creation of Health and
Wellbeing Boards and Joint Strategic Needs Assessments, there
is another opportunity to refresh the collaboration between
professionals working in planning, transport, environmental
health and public health so that collective decisions can be
made that influence both air quality and health positively.
3.3 In the UK it has been estimated that the mortality burden
of long term exposure to particulate matter (PM
2.5
) in 2008 was
equivalent to nearly 29,000 premature deaths in those aged 30
or older
7
. The Public Health Outcomes Framework data tool
shows the fraction of mortality attributable to air pollution by
local authority (range 2.7 - 8.3%, average for England 5.4%)
8
. It is
likely that removing exposure to all PM
2.5
would have a bigger
impact on life expectancy in England and Wales than eliminating
passive smoking or road traffic accidents
9
. The economic cost
from the impacts of air pollution in the UK is estimated at £9-19
billion every year which is comparable to the economic cost
of obesity (over £10 billion)
10
. In 2013, the International Agency
for Research on Cancer has identified outdoor air pollution as
causing lung cancer, without identifying the specific pollutants
that are the carcinogenic component
11
.
3.4 Nitrogen dioxide can also, independently of particulate
matter, play an adverse role in exacerbating asthma, bronchial
symptoms (even in healthy individuals), lung inflammation and
reduced lung function. Reduced lung function growth is also
linked to nitrogen dioxide exposure at concentrations currently
found in many urban areas. There is also an increasing awareness of
evidence, as summarised in the HRAPIE review by the WHO
12
, that
chronic exposure to NO
2
may be important for premature mortality
effects. The strength of this evidence is less than it is for the much
3. Links between poor air quality, human
health and the environment
Image: © Roger Barrowcliffe
10
EPUK & IAQM u GUIDANCE
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larger body of evidence for particles, with regard to the use of a
concentration-response function that is suitable for quantification
of the impact on mortality. The evidence is considered by the
Committee on the Medical Effects of Air Pollutants to be sufficient
to conclude that NO
2
is causing some of the health effects observed
in epidemiological studies
13
.
The Committee recommends that
concentration response functions for the association between NO
2
and premature mortality can be used, with some qualifications
14
.
When applied on a national basis, use of these functions suggests
that the national premature mortality burden for long term exposure
to NO
2
is equivalent to 23,000 deaths annually
15
.
3.5 Emissions of some airborne pollutants are known to damage
the health of ecosystems, often in subtle and long term ways.
Much more is now known about the effects of excess acidity
and nutrient nitrogen on plants, which have been taking place
over a long period of time. Many sensitive areas of the UK are
still adversely affected and are in an unfavourable condition,
despite the reduction in national emissions of SO
2
and NO
x
.
Agriculture is a dominant source of ammonia emissions which
contribute to acidity and nutrient nitrogen. Intensive livestock
units can be a significant local source of ammonia, for example.
As noted in the Introduction (paragraph 1.4) this guidance is not
designed to assess the impacts of air pollution on ecosystems.
3.6 The control of air pollution is the responsibility of local
authorities and other government agencies through several
Acts of Parliament and Regulations. Air pollution has many
sources and is not confined by administrative boundaries and
consequently its control requires regulatory authorities and
national government to use a wide range of policy levers to
influence air quality. Local authorities have a wide remit and their
responsibilities touch on many aspects of our lives. To achieve
their objectives they need to draw on many different resources,
some statutory, and some that rely on cooperation with others.
Good air quality is one such objective, where many players can
affect the outcome through actions taken in different places
and sometimes over long periods of time as one development
succeeds another. Determining one application in isolation may
not achieve good air quality on its own. This is often achieved
through many decisions made in different circumstances guided
by a mosaic of policies that implemented together will create
better air quality.
7
The Mortality Effects of Long-Term Exposure to Particulate Air Pollution in the United Kingdom. The Committee on the Medical Effects of Air Pollutants
(COMEAP) (2010) www.gov.uk/government/publications/comeap-mortality-effects-of-long-term-exposure-to-particulate-air-pollution-in-the-uk
8
Public Health England. (2013). Health Protection. Available: www.phoutcomes.info/public-health-outcomes-framework#gid/1000043/pat/6/ati/101/page/8/
par/E12000002/are/E06000008. (Accessed 20/1/14).
9
Comparing estimated risks for air pollution with risks for other health effects, Miller and Hurley, IOM (2006) www.iom-world.org/pubs/IOM_TM0601.pdf.
10
www.defra.gov.uk/environment/quality/air/air-quality/impacts/ 11 IARC Scientific Publication No. 161 Air Pollution and Cancer, Editors: K. Straif, A. Cohen,
and J. Samet, 2013, Lyon
12
www.euro.who.int/__data/assets/pdf_file/0006/238956/Health-risks-of-air-pollution-in-Europe-HRAPIE-project,-Recommendations-for-concentration-
response-functions-for-costbenefit-analysis-of-particulate-matter,-ozone-and-nitrogen-dioxide.pdf.
13
COMEAP (2015) Statement on the Evidence for the Effects of Nitrogen Dioxide on Health, 12 March 2015 (https://www.gov.uk/government/publications/
nitrogen-dioxide-health-effects-of-exposure).
14
www.gov.uk/government/publications/nitrogen-dioxide-interim-view-on-long-term-average-concentrations-and-mortality
15
www.gov.uk/government/uploads/system/uploads/attachment_data/file/486636/aq-plan-2015-overview-document.pdf
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Policy context
4.1 This Chapter provides a brief overview of the important
aspects of land use planning in the context of this Guidance. A
more detailed review of the land use planning system in the UK
is provided in Essential Environment
16
, a regularly updated online
and hardcopy service provided by Environmental Protection
UK. Information may also be obtained from the Government’s
various specialist websites (e.g. www.laqm.defra.gov.uk).
4.2 The 2008 Planning Act
17
introduced a change in the planning
consent regime for major or ‘nationally significant’ infrastructure
projects, for example energy, transport, water and waste. The
Localism Act 2011 makes a number of amendments to the Planning
Act concerning consent for infrastructure planning which is now
the responsibility of the Major Infrastructure Planning Unit.
4.3 Local authorities at district, county and unitary level retain
the responsibility for decisions on all other developments except
where the Secretary of State determines those applications
subject to Appeal. In arriving at a decision about a specific
proposed development the local planning authority is required to
achieve a balance between economic, social and environmental
considerations. For this reason, appropriate consideration of
issues such as air quality, noise and visual amenity is necessary.
In terms of air quality, particular attention should be paid to:
• compliance with national air quality objectives and of EU
Limit Values
18
,
19
;
•
whether the development will materially affect any air
quality action plan or strategy;
•
the overall degradation (or improvement) in local air quality; or
•
whether the development will introduce new public
exposure into an area of existing poor air quality.
4.4
The National Planning Policy Framework (NPPF) and the
Planning Policy Wales (PPW) set out planning policy for England
and Wales respectively. They place a general presumption in
favour of sustainable development, stressing the importance
of local development plans, and state that the planning system
should perform an environmental role to minimise pollution.
One of the NPPF twelve core planning principles notes that
planning should “contribute to…reducing pollution”, whilst PPW
includes a core principle that requires respect for environmental
limits such that resources are not irrecoverably depleted or the
environment irreversibly damaged. Both NPPF and PPW recognise
that to prevent unacceptable risks from air pollution, planning
decisions should ensure that new development is appropriate
for its location. The policies state that the effects of pollution
on health and the sensitivity of the area and the development
should be taken into account.
4.5 The NPPF/PPW states that: “Planning policies should sustain
compliance with and contribute towards EU limit values or national
objectives for pollutants, taking into account the presence of Air
Quality Management Areas and the cumulative impacts on air
quality from individual sites in local areas. Planning decisions should
ensure that any new development in Air Quality Management Areas
is consistent with the local air quality action plan”.
4.6 The NPPF is supported by Planning Practice Guidance (PPG),
whilst PPW is supported by Technical Advice Notes (TANs) and
Supplementary Planning Guidance. These include guiding principles on
how planning can take account of the impacts of new development
on air quality. The PPG states that “Defra carries out an annual
national assessment of air quality using modelling and monitoring
to determine compliance with EU Limit Values” and “It is important
that the potential impact of new development on air quality is taken
into account … where the national assessment indicates that relevant
limits have been exceeded or are near the limit”. The role of the local
authorities is covered by the LAQM regime, with the guidance stating
that local authority Air Quality Action Plans “identify measures that
will be introduced in pursuit of the objectives”. The PPG makes clear
that “Air quality can also affect biodiversity and may therefore impact
on our international obligation under the Habitats Directive”, and
in addition, that “Odour and dust can also be a planning concern,
for example, because of the effect on local amenity”. In Wales, a
specific link has been made between air quality and noise such that
where Air Quality Action Plans prioritise measures in terms of costs
and benefits, traffic noise
20
should also be given due consideration,
qualitatively if not quantitatively.
4.7 The PPG states that “Whether or not air quality is relevant
to a planning decision will depend on the proposed development
and its location. Concerns could arise if the development is likely
to generate air quality impact in an area where air quality is
known to be poor. They could also arise where the development
is likely to adversely impact upon the implementation of air
quality strategies and action plans and/or, in particular, lead to
a breach of EU legislation (including that applicable to wildlife)”.
4.8 The PPG sets out the information that may be required in an
air quality assessment, making clear that “Assessments should be
proportional to the nature and scale of development proposed
and the level of concern about air quality”. It also provides
examples of the types of measures to be considered. It states that
“Mitigation options where necessary, will depend on the proposed
development and should be proportionate to the likely impact”.
4. Planning Framework
12
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4.9 An overview of the context of air quality and planning at a
national, regional and local level is set out in Table 4.1. The air
quality impacts of a planning application will be judged against
the policies within these documents.
Supplementary Planning Documents and Guidance
4.10 Supplementary Planning Documents/Guidance (SPDs or
SPGs) represent guidance formally adopted by local authorities in
England. They provide additional information in relation to specific
policy areas within the Local Development Framework. Many local
authorities have now published SPGs or SPDs on air quality
21
. Often
these draw on information provided in previous versions of this
guidance. They generally set out when an air quality assessment is
required and what it should include. Some also include criteria for
assessing the significance of the impact of a proposed development.
These documents are a very useful tool for providing transparent
and consistent advice to both Development Control departments
and developers. They can also provide a means for assessing the
adequacy of an air quality assessment.
4.11 SPGs and SPDscan be taken into account when considering
planning applications, and weight accorded to them will be
increased ifthey havebeen subject to public consultation.
Appropriate air quality policies should, however, underpin the more
detailed guidance in the SPD or SPG to ensure its effectiveness.
The Planning Process
4.12 Development proposals may be submitted as outline or full
applications. Outline applications should contain sufficient detail
to allow the impacts to be properly assessed. Pre-application
discussions between developers, or their representatives, and
local authorities are encouraged to ensure an application is
complete and meets the necessary requirements. The decisions
made by local authorities should be made in accordance with the
local policies and plans, unless there are material considerations
to suggest otherwise.
4.13 The applicant may receive an unconditional permission
or, more likely, for those developments requiring an air quality
assessment, permission subject to conditions. The application
can also be refused. Outline applications may be approved
subject to reserved matters. In some circumstances conditions
or the reserved matters require an air quality assessment prior
to commencement of site works or occupation/use of a
development. This is not good practice as it is unlikely that
major changes will take place to mitigate any impacts at this
late stage in the design of a new development.
4.14 Air quality (and other) impacts can be controlled through
the application of planning conditions or through planning
obligations (often known as ‘section 106 agreements’)
22
.
Conditions are specific to the development, while planning
obligations can have a wider remit. For instance, a planning
condition might be used to require the installation of a
suitable ventilation system, while an obligation often requires
a financial contribution, for example, to require a “car club”
to be set up. Conditions and planning obligations have
different legal standing and advice from planners should be
sought to determine the appropriate approach to apply to
mitigate the air quality impacts of specific developments.
Combinations of planning conditions and obligations are
now often used to fund Low Emission Strategies. The
Community Infrastructure Levy is a more recently introduced
mechanism that requires developers to contribute to new
local infrastructure, which may be relevant to improving air
quality in some cases.
Material Considerations
4.15 The planning system recognises that, in principle, any
consideration which relates to the use and development of land
is capable of being a planning consideration. This includes air
quality. The circumstances of a particular planning application will
determine whether or not this is the case in practice. Material
considerations must be genuine planning considerations, relating
specifically to the development and use of land in the public
interest. They must also fairly and reasonably relate to the
application concerned.
4.16 Where a planning application runs counter to relevant
local policies, it is not normally permitted, unless other material
planning considerations outweigh the objections and justify
granting permission. This emphasises the importance of ensuring
that appropriate planning policies dealing with air quality are
Level Relevant Documentation
National National Planning Policy Framework
Planning Practice Guidance
Air Quality Strategy 2007
Regional
Regional Air Quality Strategy
a
Local Local Development Framework (LDF)
Supplementary Planning Documents (SPD)
Air Quality Action Plans
Local Air Quality Guidance
Neighbourhood Plans
a
For example the Mayor’s Air Quality Strategy in London
Table 4.1: Context of air quality and planning in England.
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in place. Particular attention is paid to whether such policies
are met or not during the planning appeals process. If effective
policies for air quality management are in place, either within
the LDF/P, Local Plan, or a SPD, then air quality issues can be
accounted for in decision making far more than in cases where
there are only weak or no relevant policies.
Air quality as a material consideration
4.17 Any air quality issue that relates to land use and its
development is capable of being a material planning consideration.
The weight, however, given to air quality in making a planning
application decision, in addition to the policies in the local plan,
will depend on such factors as:
• the severity of the impacts on air quality;
•
the air quality in the area surrounding the proposed development;
•
the likely use of the development, i.e. the length of time
people are likely to be exposed at that location; and
•
the positive benefits provided through other material considerations.
4.18
Chapter 7 of this Guidance explores in more detail how to
judge the significance of the air quality impacts of a development
proposal, and inform the outcome in terms of planning decisions.
4.19 Some air quality assessments will be undertaken for
development that falls within the scope of the Environmental
Impact Assessment Regulations
23
. Such assessments will need to
recognise the requirements of these Regulations, in respect of the
need to define likely significant effects and identify mitigation, for
example. This guidance has been written to take into account
the EIA regulations, although it is not written purely for their
requirements. It is also possible that the Habitats Regulations
would invoke the need for an air quality assessment, should the
development have potential for affecting a designated site of
nature conservation at the European level, i.e. a Special Area of
Conservation (SAC), a Special Protection Area (SPA) or a Ramsar
site. Such an assessment is not part of this guidance, however.
Linkages with other relevant issues
4.20 Decision-makers need to take account of a wide range of
potential impacts arising from new developments. In many cases
there are linkages between air quality and these other issues.
Examples include the use of road humps to limit traffic speeds
and improve safety, which can in turn increase emissions through
vehicles braking and then accelerating and the use of biomass
boilers to reduce climate change impacts, which can increase
emissions of particulate matter and NO
x
. It is important that
these linkages are fully understood and taken into account to
optimise the opportunities to enhance the sustainability of new
developments. This may require the input of other specialists.
16
See www.pollutioncontrolonline.org.uk or http://www.essentialenvironment.org.uk
17
www.opsi.gov.uk/acts/acts2008/ukpga_20080029_en_1.
18
The duty to meet EU Limit Values is placed on the Secretary of State and not local government.
19
The precise role of the development control process in delivering compliance with the EU limit values is uncertain, and clarification has been sought from Defra.
20
Local Air Quality Management Policy Guidance for Wales, Addendum Air Quality and Traffic Noise (2012).
21
Example in Annexe 3: www.lowemissionstrategies.org/downloads/LES_Good_Practice_Guide_2010.pdf
22
See www.communities.gov.uk/publications/planningandbuilding/circularplanningobligations.
23
The Town and Country Planning (Environmental Impact Assessment) Regulations 2011 SI no. 1824.
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Introduction
5.1 This section explains how all development proposals
can adopt good design principles that reduce emissions and
contribute to better air quality management. The roles of
the local authority and developer/applicant in the process
by which air quality and planning decisions are taken are
set out and commentary is given on how both the strategic
planning and development control processes can contribute
to good practice for all new development. The flow chart in
Figure 2 below provides an overview of the whole process,
defining the roles of the various parties and identifying
opportunities for optimising the development proposal so as
to reduce emissions. The concepts outlined in this section are
applicable to all development and can be applied regardless
of the outcome of any air quality assessment, as described
in Section 6.
Overarching Concepts in Land Use Planning for
Better Air Quality
5.2
The land-use planning and development control system
has an important role to play in driving forwards improvements
in local air quality, minimising exposure to pollution, and to
improving the health and well-being of the population.
5.3 Whilst land-use planning and development controls rarely
provide immediate solutions to improving air quality, they can
ensure that future problems are prevented or minimised.
5.4 This guidance deals primarily with the development control
process that is applied to determining individual applications.
The role of planning at the strategic level must not be
understated, however. Effective spatial planning can reduce the
need to travel by car to the workplace, schools, shopping and
leisure facilities by ensuring new dwellings are located in areas
where such facilities are readily available, or where alternative
transport modes are avaialble. Careful consideration to building
design and layout can assist in minimising exposure to future
occupants. Policies that enforce high building standards can
play an important role in reducing emissions from services
that provide heating and hot water – an increasingly important
sector as measures to tackle transport emissions are tightened.
Making Better Use of the Land-use Planning System
5.5 The land-use planning system has significant potential to influence
local air quality positively through the careful design of neighbourhoods.
Some actions which are strongly encouraged include:
•
Full integration of the inputs of the planning, transport, housing,
education and environment departments to ensure that environmental
considerations, including those related to air quality, are considered at
the earliest stages of the strategic planning processes;
• Ensuring public services are joined up and easier to access via public
transport or other sustainable choices such as cycling and walking; and
•
Giving careful consideration to the location of developments
(e.g. within the development of Site Allocation Policies)
5. Better by design
Image: © Debu55y | Fotolia.com
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a
Major applications are usually determined by the Development Control Committee; but in some cases the decision may be delegated to Planning Officers.
b
Section 106 of the Town and Country Planning Act 1990 (as amended).
c
Community infrastructure levy.
Local Planning Authority (LPA)
Pre-application discussions
Enforcement of planning requirements
Prepares AQA and issues to LPA, may provide clarification or
further information in response to comments
Consults on whether an air quality assessment (AQA) is required
Consults on the AQA methodology
Input to draft planning conditions
May provide clarification or further information in response to
comments
Input to S106/CIL
Applicant makes short representation in person
Developer submission(s) to show pre-development conditions
complied with
Consults on assessments required
Strategic Planning
Air Quality Policy(ies) in Core Document. Supplementary
Planning Document (SPD), good practice guidance,
and / or Air Quality Action Plan (AQAP) sets out local
assessment requirements, best practice/minimum
standards and financial contributions
Development Control
Determines whether an AQA is required. Informs applicant
/developer of air quality policies in plan/SPD/AQAP or
other document, and requirements for best practice for
all developments
Air Quality Officer comments
Air Quality Officer provides planning department
with comments on application including their
recommendations
Statutory bodies consulted, and comments submitted to
planning officer
Planning conditions drafted e.g. on mitigation measures
S106
b
or CIL
c
agreement e.g. contribution to mitigation or
Low Emission Strategy
Planning Officer prepares report with recommendations
for the Development Control (DC) Committee
a
DC Committee makes decision
a
. May refer matter back to
Planning Department for more information; may require
additional conditions
Agree pre-development planning conditions have been
complied with. Possibly request further information
Developer may make representations during public
consultation
Applicant / Developer
Figure 2: Role of Local Authority and Applicant/Developer in the planning process
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BOX 1: Examples of Approaches to Reducing Emissions
and Impacts
1. Air Quality and emissions mitigation guidance for
Sussex authorities
The Sussex Air Quality Partnership has prepared guidance
to assess the potential impacts of new development,
providing a consistent approach to mitigation. The
guidance follows a three stage process. The first stage
is used to screen out developments that will have very
small impacts, on the basis of their size or location. All
developments that are not screened out are required
to carry out an “emissions mitigation assessment”. This
quantifies the additional emissions generated by traffic for
the development (following a set of defined assumptions)
and then assigns a monetary value to this (over a 5 year
period, based on Defra’s damage cost approach). This
defines the value of mitigation that should be applied,
preferably on-site.
For some developments, e.g. those within an AQMA,
developments that exceed threshold criteria for parking or
traffic generation, or where new exposure is introduced, an
air quality assessment is also required, to determine the likely
significant effects.
2. West Yorkshire Air Quality and Emissions Planning
Guidance
The West Yorkshire Low Emissions Strategy Group
has published guidance for integrating air quality
considerations into land-use planning and development
management policies. The air quality assessment
process follows three stages:
Determining the classification of the development
proposal – schemes are classified as Minor, Medium or
Major based on criteria that would trigger the need for
a Transport Assessment (Medium) and those that meet
additional criteria such as lying within an AQMA, exceeding
thresholds for traffic generation etc. (Major).
Air quality impact assessment – Minor and Medium
development proposals are further screened to identify
if they will introduce new exposure, which subsequently
influences the degree of mitigation required. Major
development proposals are required to complete both a
detailed air quality assessment (to determine likely significant
effects) and a quantification of pollutant emission costs
(for traffic generation only) based on a set of defined
assumptions and using Defra’s damage cost approach.
Mitigation and compensation - the outcome of stage 2
is used to determine the level of appropriate mitigation.
Default mitigation measures are proposed for Minor, Medium
and Major development; for the latter the scale of mitigation
is related to the calculated pollution damage costs.
3. Greater London Authority – Air Quality Neutral Policy
The Mayor’s SPG on Sustainable Design and Construction
requires ultra-low NO
x
boilers in all new developments and
sets emissions standards for all new CHP and biomass plant.
The SPG also sets out guidance on the implementation of “air
quality neutral” in London. This is achieved by establishing
benchmarks for both building and transport emissions which
all new developments must comply with. Where compliance
cannot be achieved, developers are required to prepare strategies
to demonstrate how the excess will be mitigated, on or off-site.
where particularly sensitive members of the population are
likely to be present e.g. school buildings should generally be
sited 100m or more away from busy roads, in areas where
pollution concentrations are high.
Examples of Approaches to Reducing Emissions
and Impacts
5.6 A particular concern of many local authorities is that
individual developments are often shown to have a very small air
quality impact, and, as a consequence, there are few mechanisms
available to the planning officer to require the developer to
achieve lower emissions. This, in turn, leads to concerns about
the potential air quality impacts of cumulative developments as
many individual schemes, deemed insignificant in themselves,
contribute to a “creeping baseline”.
5.7 To tackle this issue, a number of authorities have developed
various approaches to identify the requirement for good practice
and design requirements at an early stage of the assessment
process. A summary of a number of these approaches is set
out in Box 1; in the majority of cases, these approaches only
consider emissions from road traffic generated by the scheme.
The basic concept is that good practice to reduce emissions and
exposure is incorporated into all developments at the outset,
at a scale commensurate with the emissions.
5.8 It is probably not practicable or appropriate to apply the
approaches described in Box 1 to very small developments which
will have only a very small impact on local air quality conditions.
An approach that is commonly used is to consider only “major”
developments, such as defined within the Town and Country
Planning (Development Management Procedure) Order (England)
2010 [(Wales) 2012]. These include developments where:
• The number of dwellings is 10 or above;
•
The residential development is carried out on a site of more
than 0.5ha where the number of dwellings is unknown;
•
The provision of more than 1000 m
2
commercial floorspace; or
• Development carried out on land of 1ha or more.
5.9 Developments which introduce new exposure into an area of
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existing poor air quality (e.g. an AQMA) should also be considered
in this context.
5.10 Principles of Good Practice
Good practice principles should be applied to all
developments that have not been screened out using
criteria such as those in paragraph 5.8. These cover both
emissions and exposure, and address both the design and
operational phases. Some examples of such principles
include the following.
Design phase
•
New developments should not contravene the Council’s
Air Quality Action Plan, or render any of the measures
unworkable;
•
Wherever possible, new developments should not create a
new “street canyon”, or a building configuration that inhibits
effective pollution dispersion;
•
Delivering sustainable development should be the key theme
of any application;
• New development should be designed to minimise public
exposure to pollution sources, e.g. by locating habitable
rooms away from busy roads, or directing combustion
generated pollutants through well sited vents or chimney stacks.
Operational phase
•
The provision of at least 1 Electric Vehicle (EV) “fast
charge” point per 10 residential dwellings and/or 1000m
2
of commercial floorspace. Where on-site parking is provided
for residential dwellings, EV charging points for each parking
space should be made.
• Where development generates significant additional
traffic, provision of a detailed travel plan (with
provision to measure its implementation and effect)
which sets out measures to encourage sustainable
means of transport (public, cycling and walking) via
subsidised or free-ticketing, improved links to bus
stops, improved infrastructure and layouts to improve
accessibility and safety.
•
All gas-fired boilers to meet a minimum standard of <40
mgNO
x
/kWh.
•
All gas-fired CHP plant to meet a minimum emissions standard of:
˚ Spark ignition engine
22
:
250 mgNO
x
/Nm
3
;
˚ Compression ignition engine
23
: 400 mgNO
x
/Nm
3
;
˚ Gas turbine
24
: 50 mgNO
x
/Nm
3
.
•
A presumption should be to use natural gas-fired installations.
Where biomass is proposed within an urban area it is to meet
minimum emissions standards of:
˚
Solid biomass boiler
25
: 275 mgNO
x
/Nm
3
and 25 mgPM/Nm
3
.
(These suggested emission benchmarks represent readily
achievable emission concentrations by using relatively simple
technologies. They can be bettered by using more advanced
control technology and at additional cost over and above the
‘typical’ installation.).
Image: © Mark6138 | Dreamstime.com
18
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22
At reference conditions of 273K, 101.3 kPa, 5%O
2
and 0% H
2
O.
23
At reference conditions of 273K, 101.3kPa, 5%O
2
and 0% H
2
O.
24
At reference conditions of 273K, 101.3 kPa, 15% O
2
and 0% H
2
O.
25
At reference conditions of 273K, 101.3 kPa, 6%O
2
and 0% O
2
26
Dickens R, Gill J, Rubin and Butterwick M (2013) Valuing impacts on air quality: Supplementary Green Book guidance. HM Treasury and Defra.
27
www.gov.uk/air-quality-economic-analysis#damage-costs-approach.
Offsetting Emissions
5.11 In addition to these good practice principles, local
authorities may wish to incorporate additional measures
to offset emissions at an early stage. It is important that
obligations to include offsetting are proportional to the
nature and scale of development proposed and the level
of concern about air quality; such offsetting can be based
on a quantification of the emissions associated with the
development. These emissions can be assigned a value, based
on the “damage cost approach” used by Defra, and then
applied as an indicator of the level of offsetting required,
or as a financial obligation on the developer. Unless some
form of benchmarking is applied, it is impractical to include
building emissions in this approach, but if the boiler and CHP
emissions are consistent with the standards as described
above then this is not essential.
5.12 An approach that has been widely used to quantify the
costs associated with pollutant emissions from transport is to:
•
Identify the additional trip rates (as trips/annum) generated
by the proposed development (this information will normally
be provided in the Transport Assessment to;
• Assume an average distance travelled of 10km/trip;
•
Calculate the additional emissions of NO
x
and PM
10
(kg/
annum), based on emissions factors in the Emissions Factor
Toolkit, and an assumption of an average speed of 50 km/h;
•
Multiply the calculated emissions by 5, to assume emissions
over a 5 year time frame;
•
Use the HM Treasury and Defra IGCB damage cost approach
26
to provide a valuation of the excess emissions, using the
currently applicable values for each pollutant
27
; and
• Sum the NO
x
and PM
10
costs.
5.13 The cost calculated by these means provides a possible
basis for defining the financial commitment required for the
offsetting emission reductions or the contribution provided
by the developers as ‘planning gain’.
5.14 Typical measures that may be considered to offset
emissions include:
• Support for and promotion of car clubs;
•
Contributions to low emission vehicle refuelling infrastructure;
•
Provision of incentives for the uptake of low emission vehicles;
•
Financial support to low emission public transport options; and
• Improvements to cycling and walking infrastructure.
5.15 Measures to offset emissions may also be applied as post
assessment mitigation.
Image: Roger Barrowcliffe
6. Undertaking an Air Quality Assessment
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Purpose
6.1 The air quality assessment is undertaken to inform the
decision making with regard to the development. It does not,
of itself, provide a reason for granting or refusing planning
permission. Almost all development will be associated with new
emissions if the development is considered in isolation. In most
cases, therefore, development will be associated with adverse
impacts. These impacts require quantification and evaluation
in the context of air quality objectives and existing air quality.
The significance of the effects arising from the impacts on
air quality will depend on a number of factors and will need
to be considered alongside the benefits of the development
in question. Development under current planning policy is
required to be sustainable and the definition of this includes
social and economic dimensions, as well as environmental.
Development brings opportunities for reducing emissions at a
wider level through the use of more efficient technologies and
better designed buildings, which could well displace emissions
elsewhere, even if they increase at the development site.
Conversely, development can also have adverse consequences for
air quality at a wider level through its effects on trip generation.
6.2 Where a development requires an air quality assessment,
this should be undertaken using an approach that is robust and
appropriate to the scale of the likely impacts. One key principle
is that the assessment should be transparent and thus, where
reasonable, all input data used, assumptions made, and the
methods applied should be detailed in the report (or appendices).
6.3 As set out in the introduction in Chapter 1, this guidance
document is not intended to replace guidance that exists for
certain types of development, notably:
• industrial developments that require a Permit;
• highways schemes promoted by Highways England; or
•
activities associated with sources of dust (e.g. mineral
extraction, waste handling, construction) or odours.
Separate guidance is available for these sources. Clearly, where
new developments are located in the vicinity of such sources,
the potential impacts of their operation on the proposed
development will need to be considered.
6.4 The guidance provided by the Environment Agency and
Highways England has a formal status, reflecting the connections
these organisations have with Government departments. This
EPUK/IAQM guidance has no such status and is not intended
as a substitute for the formal guidance.
6.5 The matter of industrial development and its regulation by
the Environment Agency, Natural Resources Wales or a local
authority deserves some further consideration in a planning
context. The guidance provided by the Environment Agency
28
for
use in assessing emissions to air is intended (in part) to assist in
the determination of Best Available Techniques for an installation
regulated under the Industrial Emissions Directive (IED). This
EPUK/IAQM guidance document has been written so as to be
complementary to the EA guidance and not a substitute for it.
The EA’s risk assessment methodology has not been designed for
conducting an assessment to accompany a planning application,
especially one undertaken for the EIA Regulations. In these
circumstances, a framework is required that allows the assessor
to describe the degree of impacts before reaching a conclusion
on significance of the effects. The EA methodology does provide
some useful elements of such a framework, however, and, where
relevant, these have been used in this guidance, partly for reasons
of consistency. It must be recognised, however, that the EA
assessment methodology and the assessment guidance in this
document serve different purposes. The EA methodology is
intended for the purpose of screening out insignificant emissions
of individual pollutants and identifying where there is a risk of
of other pollutants emitted being potentially significant in terms
of environmental effects. This excercise is carried out as part
of the impact assessment in support of an application under
the Environmental Permitting Regulations. The IAQM/EPUK
guidance is intended to provide a means of reaching a conclusion
on whether the proposed development has a likely significant
effect on local air quality, taking into account the overall severity
of the impacts and other factors as appropriate. In each case,
the concept of significance has a deliberately different meaning
and context.
This document is not intended to address impacts on nature
conservation sites, for which a different form of assessment
is required.
The need for an air quality assessment
6.6 It is established good practice to consult with the Local Planning
Authority (and/or its air quality specialists) to gain agreement on the
need for an air quality assessment in support of a planning application
and if one is required, the approach and methodology that will be
used. The Planning Practice Guidance at paragraph 6 makes this point.
There is however a prior step in the consultation process, which is
to determine the very need for an assessment. If an assessment is
required, the approach and methodology can then be constructed
to deal with the key issues driving the need for the assessment.
6.7 To inform the consultation process, it will be important to
identify the locations of any AQMAs relative to the proposed
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development, the main existing and proposed sources of
atmospheric pollution and the location of existing and proposed
human-health sensitive receptors.
6.8It is reasonable to expect that an assessment will be required
where there is the risk of a significant air quality effect, either from a
new development causing an air quality impact or creating exposure to
high concentrations of pollutants for new residents. To a large extent,
professional judgement will be required to determine whether an
air quality assessment is necessary as it is not possible to apply an
exact and precise set of threshold criteria to cover the wide variety
of development proposals. The following tables provide criteria that
may be useful to guide the consultation process in establishing the
need for an assessment. They separately consider:
•
the impacts of existing sources in the local area on the
development; and
• the impacts of the development on the local area.
6.9 Where an air quality assessment is identified as being
required, this may be either a Simple or a Detailed Assessment.
A Simple Assessment is one relying on already published
information and without quantification of impacts, in contrast
to a Detailed Assessment that is completed with the aid of a
predictive technique, such as a dispersion model. Much of the
discussion in this Section relates to Detailed Assessments. The
use of a Simple Assessment may be appropriate, where it will
clearly suffice for the purposes of reaching a conclusion on the
significance of effects on local air quality. A Simple Assessment
will be appropriate, if it can provide this evidence. Similarly, it
may be possible to conduct a quantitative assessment that does
not require the use of a dispersion model run on a computer.
6.10 The criteria provided are precautionary and should be
treated as indicative. They are intended to function as a sensitive
‘trigger’ for initiating an assessment in cases where there is a
possibility of significant effects arising on local air quality. This
possibility will, self-evidently, not be realised in many cases.
The criteria should not be applied rigidly; in some instances, it
may be appropriate to amend them on the basis of professional
judgement, bearing in mind that the objective is to identify
situations where there is a possibility of a significant effect on
local air quality.
6.11 In certain circumstances, it may be necessary to consider
whether the site itself is suitable for the introduction of new
emission sources. This could be because the neighbouring land
use has particular sensitivities to increased exposure to air
pollutants. It is not possible, or desirable, to set criteria that
would define such circumstances. In practice, it is more likely
that an assessment would reach a conclusion taking any local
factors into account.
Impacts of the Local Area on the Development
6.12 There may be a requirement to carry out an air
quality assessment for the impacts of the local area’s
emissions on the proposed development itself, to assess
the exposure that residents or users might experience.
This will need to be a matter of judgement and should
take into account:
•
the background and future baseline air quality and whether
this will be likely to approach or exceed the values set by
air quality objectives;
•
the presence and location of Air Quality Management
Areas as an indicator of local hotspots where the air quality
objectives may be exceeded;
Table 6.1: Stage 1 Criteria
•
the presence of a heavily trafficked road, with emissions
that could give rise to sufficiently high concentrations of
pollutants (in particular NO
2
), that would cause unacceptably
high exposure for users of the new development; and
• the presence of a source of odour and/or dust that may
affect amenity for future occupants of the development.
Criteria to Proceed to Stage 2
A. If any of the following apply:
• 10 or more residential units or a site area of more than
0.5ha
• more than 1,000 m
2
of floor space for all other uses or a
site area greater than 1ha
B. Coupled with any of the following:
• the development has more than 10 parking spaces
•
the development will have a centralised energy facility or
other centralised combustion process
Note: Consideration should still be given to the potential
impacts of neighbouring sources on the site, even if an
assessment of impacts of the development on the surrounding
area is screened out.
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The development will: Indicative Criteria to Proceed to an Air Quality Assessment
a
1. Cause a significant change in Light Duty Vehicle (LDV)
traffic flows on local roads with relevant receptors. (LDV
= cars and small vans <3.5t gross vehicle weight).
A change of LDV flows of:
- more than 100 AADT within or adjacent to an AQMA
- more than 500 AADT elsewhere.
2. Cause a significant change in Heavy Duty Vehicle (HDV)
flows on local roads with relevant receptors. (HDV =
goods vehicles + buses >3.5t gross vehicle weight).
A change of HDV flows of:
- more than 25 AADT within or adjacent to an AQMA
- more than 100 AADT elsewhere.
3. Realign roads, i.e. changing the proximity of receptors
to traffic lanes.
Where the change is 5m or more and the road is within an
AQMA.
4. Introduce a new junction or remove an existing
junction near to relevant receptors.
Applies to junctions that cause traffic to significantly change
vehicle accelerate/decelerate, e.g. traffic lights, or roundabouts.
5. Introduce or change a bus station. Where bus flows will change by:
- more than 25 AADT within or adjacent to an AQMA
- more than 100 AADT elsewhere.
6. Have an underground car park with extraction system. The ventilation extract for the car park will be within 20 m of a
relevant receptor.
Coupled with the car park having more than 100 movements per
day (total in and out).
7. Have one or more substantial combustion processes,
where there is a risk of impacts at relevant receptors.
NB. this includes combustion plant associated with
standby emergency generators (typically associated with
centralised energy centres) and shipping.
Typically, any combustion plant where the single or combined
NO
x
emission rate is less than 5 mg/sec
a
is unlikely to give rise
to impacts, provided that the emissions are released from a vent
or stack in a location and at a height that provides adequate
dispersion.
In situations where the emissions are released close to buildings
with relevant receptors, or where the dispersion of the plume
may be adversely affected by the size and/or height of adjacent
buildings (including situations where the stack height is lower
than the receptor) then consideration will need to be given to
potential impacts at much lower emission rates.
Conversely, where existing nitrogen dioxide concentrations are
low, and where the dispersion conditions are favourable, a much
higher emission rate may be acceptable.
Impacts of the Development on the Local Area
6.13 In the case of an assessment of the impacts of a development
in the local area, a two-stage approach is suggested. The first
stage is intended to screen out smaller development and/
or developments where impacts can be considered to have
insignificant effects
29
. The second stage relates to specific
details regarding the proposed development and the likelihood
of air quality impacts.
6.14 Stage 1 requires any of the criteria under (A) coupled
with any of the criteria under (B) in Table 6.1 to apply before
it is considered appropriate to proceed to Stage 2. If none
of the criteria are met then there should be no requirement
to carry out an air quality assessment for the impact of the
proposed development on the local area, and the impacts can
be considered to have insignificant effects.
Table 6.1 sets out the Stage 1 criteria designed to remove the
need to assess impacts arising from small developments.
6.15
The criteria in Table 6.2 provide more specific guidance
as to when an air quality assessment is likely to be required
Table 6.2: Indicative criteria for requiring an air quality assessment
a
As a guide, the 5 mg/s criterion equates to a 450 kW ultra low NO
x
gas boiler or a 30kW CHP unit operating at <95mg/Nm
3
. Users
of this guidance should quantify the NO
x
mass emission rate from the proposed plant, based on manufacturers’ specifications
and operational conditions.
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to assess the impacts of the proposed development on
the local area. The criteria are more stringent where the
traffic impacts may arise on roads where concentrations are
close to the objective. The presence of an AQMA is taken
to indicate the possibility of being close to the objective,
but where whole authority AQMAs are present and it is
known that the affected roads have concentrations below
90% of the objective, the less stringent criteria are likely
to be more appropriate.
6.16 Where an air quality assessment is identified as being
required, then this may take the form of either a Simple
Assessment or a Detailed Assessment (see paragraph 6.9 for more
details). In other words, exceeding a screening criterion in
Table 6.2 does not automatically lead to the requirement for
a Detailed Assessment. The principle underlying this guidance
is that any assessment should provide enough evidence that will
lead to a sound conclusion on the presence, or otherwise, of a
significant effect on local air quality. A Simple Assessment will
be appropriate, if it can provide this evidence.
6.17 If none of the criteria are met, then there should be
no requirement to carry out an air quality assessment for
the impact of the development on the local area, and the
impacts can be considered as having an insignificant effect.
This should be agreed with the local planning authority. It
may still be necessary to carry out calculations of emissions,
as required by some location authorities (e.g. the GLA’s SPG
on Sustainable Design and Construction (2014) or the Sussex
Air Quality Partnership’s Air Quality and Emissions Mitigation
Guidance for Sussex Authorities (2013) updated January 2014).
Content of an air quality assessment
6.18
The intent of an air quality assessment is to demonstrate
the likely changes in air quality or exposure to air pollution, as a
result of a proposed development. Often these changes will be
quantified, although in some instances a qualitative assessment
will be sufficient. Ultimately, the planning authority has to use
this information to form its own view on the “significance” of
the effects of air quality impacts, and thereby the priority given
to air quality concerns in determining the application. The
assessment therefore needs to provide sufficient information
to allow this decision to be made.
6.19 In some circumstances, there will be an existing
permission for development on the site that has not yet been
exercised. In the planning system, the estimated emissions
from the existing permission could be considered as part of
the future baseline and thus a revised application for the
site would give rise to an incremental change emission from
that associated with the extant permission. This guidance
recommends that impacts be assessed for the new permission
sought against the current baseline for the site, disregarding
the extant permission; this will reflect the ‘real world’ increase
experienced by receptors.
6.20 It is important that an agreement is reached between
the applicant and the local authority as to the proposed
assessment methodology. The basis of the assessment should
be to compare the air quality following completion of the
development with that expected at that time without the
development (the future ‘baseline’). Comparison with existing
conditions will also be required, as current conditions are
those with which people are familiar. There are three basic
steps in an assessment:
i.
Assess the existing air quality in the study area (existing baseline);
ii. Predict the future air quality without the development in
place (future baseline which may or may not include the
contribution of committed development);
iii.
Predict the future air quality with the development in place
(with development).
6.21 The possibility of cumulative impacts should also be
considered. Therefore, there may be a case for modelling another
future scenario, with committed development excluded, to
allow the cumulative impact of all such future developments
with planning permission to be assessed as one combined
impact at selected receptors. In most circumstances it is more
likely that committed development would be included in the
future baseline where the information exists to facilitate this.
It is difficult to include other planning applications yet to be
determined, as the outcome is not certain.
6.22
The report prepared detailing the results of the assessment should
contain the following information (but not necessarily in this order):
a.
Relevant details of the proposed development. A
description containing information relevant to the air
quality assessment should be provided, although a fully
detailed description of the proposal is not required. This
should identify any on-site sources of pollution and an
overview of the expected traffic changes or the changes
in emissions from the site for a specified year, e.g. the
opening year or year the project is completed if phased.
A brief introduction to the sensitivity of the area should
also be provided, noting the presence of an AQMA and any
nearby sources that may affect the local air quality. The
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proposed location of any sensitive receptors in relation to
these nearby sources should be described. An introduction
to the pollutants and sources to be assessed should be
provided and, if appropriate, those that have been scoped
out of further assessment.
b.
The policy context for the assessment. This should summarise
the national and local policies that should be taken into
account in the assessment. In London this will also include
the Mayor’s policies. This is especially important where there
are local policies designed to improve air quality.
c.
Description of the relevant air quality standards and
objectives. Most air quality assessments will be carried
out to assess compliance with UK air quality objectives.
d.
The basis for determining significance of effects arising
from the impacts. The descriptors used for describing the
severity of impacts should be set out, together with the
basis for determining the significance of the effects arising
from air quality impacts.
e.
Details of the assessment methods. This section should
provide details of the methods, including the model (and
version number) and the input data used for the assessment
and any assumptions that have been made. Where a
commonly applied method is used, a detailed description of
the model itself is not required. Details should be provided
on all local input data and assumptions, including:
• the emission data and their source, with details where
non-standard data are used;
• source of the meteorological data, with a description
of how representative they are of the conditions in the
vicinity of the proposed development;
• baseline pollutant concentrations;
• background pollutant concentrations;
• choice of baseline year;
• basis for NO
x
:NO
2
calculations.
There will be some variation between requirements for
reporting data relating to point sources and road traffic. The
former will have some physical properties of the emission to
be reported, i.e. stack height, diameter, emission velocity and
exit temperature. The latter will require details of assumptions
made regarding emission factors and features of the traffic
flows used in the model, such as speeds and vehicles types,
e.g. percentage of heavy duty vehicles (HDVs) in the traffic.
f.
Model verification. This will normally be expected for
modelling of road traffic emissions, but is not practicable for
point-source modelling. If verification is not done, then some
justification or explanation will be required. Model verification
involves a comparison of the predicted versus measured
concentrations, and allows an adjustment to be made to
account for systematic errors. Such errors may include
uncertainties in traffic flow, vehicle emission factors and
estimated background concentrations, as well as limitations
of the model to represent dispersion in settings where air
flow is affected by roadside buildings, trees etc.. Model
verification will be important, especially where predicted
concentrations are close to the objective, and should be
based on the most appropriate available monitoring data
(and for some schemes it may be necessary to carry out
specific monitoring to allow robust model verification to be
undertaken). A more complete description of the approach to
model verification is provided in LAQM Technical Guidance
30
.
Full details of the verification should be provided in the
assessment.
g.
Identification of sensitive locations. Local receptors should
be identified, including residential and other properties
close to and within the proposed development, as well as
alongside roads significantly affected by the development,
even if well away from the development site, and especially
if within AQMAs. These receptors will represent locations
where people are likely to be exposed for the appropriate
averaging time (dependent on the air quality objective being
assessed against).
h. Description of baseline conditions. The findings of any site
visit(s) and/or desktop investigations will be set out, noting
sources that may affect local air quality. A description of
available monitoring data will be important to help define
baseline conditions and put the model results into context.
Where monitoring data are included in the report, it will be
important to include details of the monitoring locations,
the monitoring method, sampling period, data capture and
any adjustments applied to the data, such as diffusion tube
bias adjustment factors. Reference should also be made
to the background maps produced by Defra, together with
any adjustments of these mapped values to take account of
local monitoring (but only where the monitoring is at true
background sites). Reference should also be made to the
Defra maps showing sections of road where the limit value
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is exceeded, as these represent the ‘official’ exceedences of
the limit value, as reported to the European Commission.
These maps are only available (at the time of writing) for
2013 and not for any future years.
i.
Assessment of impacts. Results of modelling the ‘with
development’ scenario should be clearly set out in tables,
and where appropriate as concentration contours on
maps of the study area. Comparisons should be made
with the ‘no development’ conditions. Differences in
concentrations between ‘with development’ and ‘no
development’ conditions should also be tabulated.
Descriptions of the impacts at the individual receptors
should be provided (see section below), taking into account
the absolute concentrations in relation to the air quality
objectives. A comment on the sensitivity of the results to
input choices is desirable, so that a view make be taken
of the uncertainties.
j.
Description of construction phase impacts. These impacts
will relate primarily to dust emissions, which give rise to
dust soiling and elevated PM
10
concentrations, although
construction plant and vehicles may need assessment.
The assessment should take into consideration the
likely activities, duration and mitigation measures to be
implemented. The distance over which impacts are likely
to occur and an estimate of the number of properties likely
to be affected should be included. This assessment should
follow the guidance set out by the IAQM
31
.
k.
Cumulative impacts and effects. In many cases, the impact
of the development being assessed will have a cumulative
effect with other planned developments, which may or may
not have planning permission. Where these developments
have been granted planning consent and are therefore
‘committed’ developments, their impacts should be
assessed cumulatively with those of the application site.
The contribution of these committed developments should
be accounted for in the ‘future baseline’, provided that their
contributions can be quantified. This situation can arise when
several such developments are contributing additional road
traffic on one stretch of road. In some particular cases, there
may be another notable proposed development (without
planning permission) in close proximity that could contribute
an impact at receptors in combination with the primary
development being assessed. In these circumstances, it
may be necessary to quantify this combined impact for
selected receptors and assess it against the future baseline.
These occasions and the need for this form of scenario
assessment will be rare.
l.
Mitigation measures. In those cases where a significant effect
is identified then the measures to be employed to avoid,
reduce and, where appropriate, offset this effect should be
set out. Even where the effect is judged to be insignificant,
consideration should be given to the application of good
design and good practice measures, as outlined in Chapter 5.
m. Summary of the assessment results. This should include:
•
Impacts during the construction phase of the development
(usually on dust soiling and PM
10
concentrations);
•
Impacts on existing receptors during operation (usually
on concentrations of nitrogen dioxide, PM
10
and PM
2.5
);
•
Impacts of existing sources on new receptors,
particularly where new receptors are being introduced
into an area of high pollution;
•
Any exceedances of the air quality objectives arising
as a result of the development, or any worsening of
a current breach (including the geographical extent);
•
Whether the development will compromise or
render inoperative the measures within an Air
Quality Action Plan, where the development affects
an AQMA;
•
The significance of the effect of any impacts identified; and
• Any apparent conflicts with planning policy.
6.23 Most assessments are carried out for the first year of the
proposed development’s use, as this will generally represent the
worst-case scenario. This is because background concentrations
of some pollutants are predicted to decline in future years, as
emissions from new vehicles are reduced by the progressive
introduction of higher emissions standards. Where development
is phased, however, it may also be appropriate to assess conditions
for the opening years of each new phase.
Agreement of datasets and methodologies
6.24 Before undertaking an assessment, every effort should be
made to obtain agreement between the planning authority and
the assessor on the appropriate datasets and methodologies to
be used, as described above.
6.25 It is important to recognise that the focus of the procedures
used by local authorities to prepare their LAQM reports is designed
specifically for the purpose of identifying whether any air quality
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objectives are likely to be exceeded. An air quality assessment for
a development will need to go beyond this, with attention given
to defining the magnitude of the changes that will take place, even
where objectives are not exceeded. Nevertheless, the technical
guidance provided by Defra to help local authorities carry out
their LAQM duties includes some useful information on carrying
out an air quality assessment.
6.26
In some cases, it may be appropriate to carry out a period
of air quality monitoring as part of an air quality assessment.
This may be particularly helpful where new relevant exposure
is proposed in a location with a complex road layout and/
or topography, which may be difficult to model, or where
there are no data available to verify the model. Monitoring
should ideally be carried out for a minimum of six months
using a methodology and locations agreed with the local
authority. Where monitoring is carried out for less than a
year, the results will need to be adjusted to an annual mean
equivalent using the methodology described in the Technical
Guidance provided by Defra. This will add to the uncertainty
associated with any model verification and adjustment, and
this should be recognised.
Table 6.3: Impact descriptors for individual receptors.
Long term average
Concentration at receptor
in assessment year
% Change in concentration relative to Air Quality Assessment Level (AQAL)
1 2-5 6-10 >10
75% or less of AQAL Negligible Negligible Slight Moderate
76-94% of AQAL Negligible Slight Moderate Moderate
95-102% of AQAL Slight Moderate Moderate Substantial
103-109% of AQAL Moderate Moderate Substantial Substantial
110% or more of AQAL Moderate Substantial Substantial Substantial
Explanation
1. AQAL = Air Quality Assessment Level, which may be an air quality objective, EU limit or target value, or an Environment
Agency ‘Environmental Assessment Level (EAL)’.
2. The Table is intended to be used by rounding the change in percentage pollutant concentration to whole numbers, which
then makes it clearer which cell the impact falls within. The user is encouraged to treat the numbers with recognition of their
likely accuracy and not assume a false level of precision. Changes of 0%, i.e. less than 0.5%, will be described as Negligible.
3. The Table is only designed to be used with annual mean concentrations.
4. Descriptors for individual receptors only; the overall significance is determined using professional judgement (see Chapter
7). For example, a ‘moderate’ adverse impact at one receptor may not mean that the overall impact has a significant effect.
Other factors need to be considered.
5. When defining the concentration as a percentage of the AQAL, use the ‘without scheme’ concentration where there is a
decrease in pollutant concentration and the ‘with scheme;’ concentration for an increase.
6. The total concentration categories reflect the degree of potential harm by reference to the AQAL value. At exposure less
than 75% of this value, i.e. well below, the degree of harm is likely to be small. As the exposure approaches and exceeds
the AQAL, the degree of harm increases. This change naturally becomes more important when the result is an exposure
that is approximately equal to, or greater than the AQAL.
7.
It is unwise to ascribe too much accuracy to incremental changes or background concentrations, and this is especially
important when total concentrations are close to the AQAL. For a given year in the future, it is impossible to define the
new total concentration without recognising the inherent uncertainty, which is why there is a category that has a range
around the AQAL, rather than being exactly equal to it.
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Describing the impacts
6.27
It is useful for all parties involved in the planning process to
use a consistent approach for the description of the impacts. The
EIA process requires the magnitude of changes to be set out and
taken into account. In many instances there is also a desire to use a
consistent descriptive terminology across all environmental impacts
within an environmental statement so that, for example, ecological
and noise impacts can be described using the same terminology as
applied to air quality. The assessment may use its own set of criteria
to define magnitude, but the important matter to be concluded is
the likely significant effects of the impacts on air quality. There is,
therefore, a two stage process to be followed in the assessment:
• a qualitative or quantitative description of the impacts on
local air quality arising from the development; and
•
a judgement on the overall significance of the effects of any impacts.
6.28 The impacts are usually assessed at selected ‘receptors’.
It can also be helpful to present the changes in concentrations
across the study area as a whole, using concentration isopleths
on a map of the area, as this will help to inform the decision
as to whether the effect is significant or not (by describing the
geographical extent over which impacts occur and by helping
identify the sensitive receptors that might be affected).
6.29 The framework for the assessment of impacts should be capable
of application to all types and scales of development. It cannot simply
reflect a response to small scale developments, or conversely, to the
largest, and should be able to consider point and diffuse sources as
well as traffic impacts, and a wide range of pollutants.
6.30 For air quality impacts arising from surrounding sources
on new occupants of a development, then the impacts are best
described in relation to whether an air quality objective will not be
met, or is at risk of not being met. An exceedance of the objective
value is likely to be considered as being significant, an aspect that
is considered further in paragraph 7.13.
6.31 In the case of the impacts of a development on the
surrounding area, a practical way of assigning a meaningful
description to the degree of an impact is to express the magnitude
Image: © Roger Barrowcliffe
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of incremental change as a proportion of a relevant assessment
level and then to examine this change in the context of the new
total concentration and its relationship with the assessment
criterion. In this document, the term Air Quality Assessment
Level or AQAL has been adopted, as it covers all pollutants, i.e.
those with and without formal standards. In many cases, the
AQAL will be the air quality objective value. (Note that impacts
may be adverse or beneficial, depending on whether the change
in concentration is positive or negative.)
6.32 One advantage of this approach is that it avoids the
need for individual pollutants to have their own tailored
method of assessment. Since air quality standards are set
on the basis of harm, it is reasonable to assume that the
degree of harm is represented by the margin by which the
AQAL is exceeded. This concept is not universally true
and many pollutants exert an effect on human health at
exposures that are below the standard
32
. It does, however,
provide a sound and consistent basis for a framework for
the assessment of impacts. Where legislative standards do
not exist for a particular pollutant, it is common practice
to adopt the Environmental Assessment Level from the
Environment Agency’s list in its risk assessment methodology,
which can be used as the AQAL.
6.33 The suggested framework for describing the impacts on
the basis set out above is set out in Table 6.3. The term AQAL is
used to include air quality objectives or limit values, where these
exist. Users of the impact descriptors set out in Table 6.3 are
encouraged to follow the explanatory notes carefully and recognise
the spirit in which they apply. In particular, the intention is that
the descriptors should not be applied too rigidly and assessors
should recognise the inevitable uncertainties embedded within
the process of their determination.
6.34 Most particulate matter from combustion processes
(including road traffic) occurs in the PM
2.5
fraction. The
AQAL for PM
2.5
is lower than that for PM
10
, and this therefore
represents the more conservative approach for these sources.
The application of Table 6.3 for PM
2.5
is straightforward, given
that the AQAL is expressed as an annual mean. In assessing
road traffic sources, however, regard must also be given to
emissions from brake/tyre wear and road abrasion, which
are predominantly in the 2.5-10 μm fraction. Consequently,
PM
10
is the more appropriate pollutant to assess in these
circumstances. For the assessment of PM
10
, Table 6.3 should
be applied using an AQAL of 40 μg/m
3
as an annual mean;
in addition, consideration should also be given to the daily
mean AQAL. This can be done using a derived value for
the annual mean based on the number of days exceeding a
daily mean concentration of 50 μg/m
3
being no more than
35 times per year. (The equation in LAQM.TG16 shows an
annual mean of 32 μg/m
3
equating to 35 days at or above
50 μg/m
3
).
6.35 The number of significant figures to which concentrations
should be reported should reflect the accuracy associated
with predicted changes and the knowledge of background
concentrations. This is ultimately a compromise between
reducing the number in recognition of the uncertainty associated
with air quality calculations and the need to contribute to the
decision making process by being able to demonstrate a small but
widespread change, if one exists. Three significant figures may be
appropriate, e.g. 0.403, 4.03, or 40.3 etc. There may be occasions,
however, when it is better to present results to two significant
figures, depending on professional judgement regarding the
accuracy of the data
33
. Any rounding of the data should only be
applied after any calculations have been completed.
6.36 For most road transport related emissions, and diffuse
emissions associated with development, long term average
concentrations are the most useful for evaluating the severity
of impacts. For any point source, some consideration must
also be given to the impacts resulting from short term, peak
concentrations of those pollutants that can affect health
through inhalation. The Environment Agency uses a threshold
criterion of 10% of the short term AQAL as a screening criterion
for the maximum short term impact. This is a reasonable
value to take and this guidance also adopts this as a basis
for defining an impact that is sufficiently small in magnitude
to be regarded as having an insignificant effect. Background
concentrations are less important in determining the severity
of impact for short term concentrations, not least because
the peak concentrations attributable to the source and the
background are not additive.
6.37 Short term concentrations in this context are those
averaged over periods of an hour or less. These are exposures
that would be regarded as acute and will occur when a plume
from an elevated source affects airborne concentrations
experienced by a receptor over an hour or less.
6.38 Impacts expressed using an averaging time of a day are
not amenable to this form of assessment of short term impacts,
since the plume spread will be much too wide over the course of
a day, leading to a different kind of exposure to the peak short
term concentrations. This is a problem chiefly with respect to
PM
10
and the expression of its limit value and objective as a 24
hour mean. (In this context, note that the following paragraphs
do not refer to 24 hour means.) Paragraph 6.34 explains how
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the objective value for the daily mean PM
10
concentration
can be translated into an equivalent annual mean value for
the AQAL.
6.39
Where such peak short term concentrations from an
elevated source are in the range 11-20% of the relevant AQAL,
then their magnitude can be described as small, those in the
range 21-50% medium and those above 51% as large. These
are the maximum concentrations experienced in any year
and the severity of this impact can be described as slight,
moderate and substantial respectively, without the need to
reference background or baseline concentrations. That is not
to say that background concentrations are unimportant,but
they will, on an annual average basis, be a much smaller
quantity than the peak concentration caused by a substantial
plume and it is the contribution that is used as a measure
of the impact, not the overall concentration at a receptor.
This approach is intended to be a streamlined and pragmatic
assessment procedure that avoids undue complexity.
6.40 In most cases, the assessment of impact severity
for a proposed development will be governed by the
long-term exposure experienced by receptors and it will
not be a necessity to define the significance of effects
by reference to short-term impacts. The severity of
the impact will be substantial when there is a risk that
the relevant AQAL for short-term concentrations is
approached through the presence of the new source,
taking into account the contribution of other prominent
local sources.
28
www.gov.uk/guidance/air-emissions-risk-assessment-for-your-environmental-permit
29
Taking account of criteria published in: a) The Town and Country Planning (Development Management Procedure) (England) Order 2010 – 2010 No. 2184
[(Wales) Order 2012, No 801(W11)] (HMSO), b) The GLA’s Supplementary Planning Guidance (SPG) on Sustainable Design and Construction (2014) and c) The
Sussex Air Quality Partnership’s Air Quality and Emissions Mitigation Guidance for Sussex Authorities (2013) v January 2014. The latter still requires a calculation
of emissions even if an assessment is not required.
30
laqm.defra.gov.uk/technical-guidance. Separate Technical Guidance is available for London at: www.london.gov.uk/sites/default/files/llaqm_technical_
guidance_llaqm.tg_16.pdf.
31
http://iaqm.co.uk/text/guidance/construction-dust-2014.pdf.
32
This is in part reflected in the description of impacts as being ‘slight’ or ‘moderate’, even when concentrations are well below the AQAL (see Table 6.3).
33
This is not the case where the changes being reported are small, as it could lead to the presentation of misleading data. For example a change of 0.2 μg/m
3
for the annual mean nitrogen dioxide concentration from 40.2 to 40.4 μg/m
3
would be presented as 40 μg/m
3
without and 40 μg/m
3
with the scheme, while
the same change applied to 40.4 μg/m
3
without to 40.6 μg/m
3
with the scheme, would be presented as 40 μg/m
3
without and 41 μg/m
3
with the scheme.
EPUK & IAQM Land-Use Planning & Development Control: Planning For Air Quality 29
EPUK & IAQM u GUIDANCE
Planning For Air Quality
7.1 Impacts on air quality, whether adverse or beneficial, will
have an effect on human health that can be judged as ‘significant’
or ‘not significant’. This is the primary requirement of the EIA
regulations, but is also relevant to other air quality assessments.
It is important to distinguish between the meaning of ‘impact’
and ‘effect’ in this context. An impact is the change in the
concentration of an air pollutant, as experienced by a receptor.
This may have an effect on the health of a human receptor,
depending on the severity of the impact and other factors
that may need to be taken into account. Judging the severity
of an impact is generally easier than judging the significance of
an effect.
7.2 The significance of effect that any proposed development
might have will also be judged at two separate stages of the
development control process, as follows:
• the first is within the air quality report accompanying the
planning application; while
•
the second is when the local authority’s air quality specialist
makes his/her recommendations to the planning officer.
7.3 These are mutually exclusive requirements serving different
purposes. Ultimately, any disputes on these matters are dealt
with by the judgement of the planning committee and/or a
planning inspector following a planning appeal. A significant air
quality effect is not, of itself, a reason for refusal of a planning
application; that decision will be the outcome of a careful
consideration of a number of factors by a planning committee
(or a planning inspector/Secretary of State), air quality being
just one of the factors.
7.4 The assessment framework for describing impacts can be
used as a starting point to make a judgement on significance of
effect, but there will be other influences that might need to be
accounted for. The impact descriptors set out in Table 6.3 are
not, of themselves, a clear and unambiguous guide to reaching a
conclusion on significance. These impact descriptors are intended
for application at a series of individual receptors. Whilst it may
be that there are ‘slight’, ‘moderate’ or ‘substantial’ impacts at
one or more receptors, the overall effect may not necessarily
be judged as being significant in some circumstances.
7.5 One of the relevant factors in the judgement of the overall
significance of effect may relate to the potential for cumulative
impacts and, in such circumstances, several impacts that are
described as ‘slight’ individually could, taken together, be regarded
as having a significant effect for the purposes of air quality
management in an area, especially where it is proving difficult to
reduce concentrations of a pollutant. Conversely, a ‘moderate’
or ‘substantial’ impact may not have a significant effect if it is
confined to a very small area and where it is not obviously the
cause of harm to human health.
7.6 Often, it is possible to be very clear when an impact is
sufficiently slight that it has no effect on receptors and can
therefore be described unequivocally as ‘not significant’
34
. In
the opposite case, when an impact is clearly substantial, it will
be obvious that there is potential for a significant effect. The
problem lies in the intermediate region where there is likely to be
uncertainty on the transition from insignificant to significant. In
those circumstances where a single development can be judged
in isolation, it is likely that a ‘moderate’ or ‘substantial’ impact will
give rise to a significant effect and a ‘negligible’ or ‘slight’ impact
will not have a significant effect, but such judgements are always
more likely to be valid at the two extremes of impact severity.
7.7 Any judgement on the overall significance of effect of a
development will need to take into account such factors as:
•
the existing and future air quality in the absence of the development;
•
the extent of current and future population exposure to
the impacts; and
•
the influence and validity of any assumptions adopted when
undertaking the prediction of impacts.
Other factors may be relevant in individual cases.
7.8 The population exposure in many assessments will be
evaluated by describing the impacts at individual receptors.
Often, these will be chosen to represent groups of residential
properties, for example, and the assessor will need to consider
the approximate number of people exposed to impacts in
the various different categories of severity, in order to reach
a conclusion on the significance of effect. An individual property
exposed to a moderately adverse impact might not be considered
a significant effect, but many hundreds of properties exposed to
a slight adverse impact could be. Such judgements will need to
be made taking into account multiple factors and this guidance
avoids the use of prescriptive approaches.
7.9 A judgement of the significance should be made by a
competent professional who is suitably qualified. The reasons
for reaching the conclusions should be transparent and set
out logically. Whilst the starting point for the assessment of
significance is the degree of impact, as defined by Table 6.3, this
should be seen as one of the factors for consideration, not least
because the outcome of this assessment procedure applies to
a receptor and not the overall impact.
7. Assessing Significance
30
EPUK & IAQM u GUIDANCE
Planning For Air Quality
7.10
The judgement on significance relates to the consequences
of the impacts; will they have an effect on human health that
could be considered as significant? In the majority of cases, the
impacts from an individual development will be insufficiently
large to result in measurable changes in health outcomes that
could be regarded as significant by health care professionals.
In reality, therefore, it is the impact on local air quality that is
used as a proxy for assessing effects on health.
7.11
There are no viable means of assigning significance to health
outcomes as yet, even though quantification of mortality and
morbidity effects from certain air pollutants at the population
level has evolved to a point where reasonable confidence in the
estimates exist. Part of any judgement on the significance of health
effects would incorporate the size or the population exposed to
changes in concentrations. Any judgement on the significance of
effects on health is part of a Health Impact Assessment and not
the air quality assessment being described here.
7.12 For local authorities, there may also be a question of
meeting air quality objectives as part of their obligations under
Local Air Quality Management Regulations. As has already
been noted, the presence of an AQMA that may be affected
by a proposed development will increase the sensitivity of the
application and any accompanying assessment. The impacts
descriptor table acknowledges this and points to a conclusion
of significant effect in cases where concentrations of a regulated
pollutant are in excess of the objective value. Where the baseline
concentrations are close to the objective value at a receptor,
but not exceeding it, a case may be made for the development’s
predicted contribution being significant. It will always be difficult,
however, to attribute the exceedance of an objective to any
individual source.
7.13 Where the air quality is such that an air quality objective
at the building façade is not met, the effect on residents or
occupants will be judged as significant, unless provision is made
to reduce their exposure by some means. For people working at
new developments in this situation, the same will not be true
as occupational exposure standards are different, although any
assessment may wish to draw attention to the undesirability of
the exposure.
34
The precise role of the development control process in delivering compliance with the EU limit values is uncertain, and clarification has been sought from
Defra. Until unambiguous clarification from a Government department is provided on this matter, which confirms that any increase in concentration should
not be permitted where an EU limit value is not met, then the precise extent to which an impact may need to be regarded as a significant effect in this context
and in such areas is unclear.
Image: © Roger Barrowcliffe
EPUK & IAQM Land-Use Planning & Development Control: Planning For Air Quality 31
EPUK & IAQM u GUIDANCE
Planning For Air Quality
EPUK & IAQM u GUIDANCE
Planning For Air Quality
8. Mitigating Impacts
8.1
Developers should be encouraged to submit proposals that
are consistent with the principles outlined in Chapter 5. This will
assist in reducing emissions and therefore in reducing impacts.
In those circumstances where the assessment concludes that
there will be a significant effect, then there is a requirement
for mitigating these residual impacts, where this is feasible.
Where the development proposal has already adopted the best
practice for its type, there may be a need to implement further
measures of the kind already incorporated or provide for some
form of compensating pollution control measures in the local
area. Where practicable, the impact of the mitigation measures
proposed should be quantified.
8.2
The type of measures proposed to reduce air quality impacts
will depend on the nature and scale of the proposed development.
Where the proposal is for a small number of new residential
units in an area of high pollutant concentrations, it would be
reasonable to examine design and ventilation arrangements to
reduce the impact of the external environment on occupants
in the building. Where the proposed development is larger and
its impact on air quality greater, then wider measures could be
considered, such as improvements in the emissions from public
transport and funding for traffic management measures over a
wider area. Large industrial developments subject to control
under the Environmental Permitting Regulations should conform
to best practice within the relevant sector and in consultation
with the regulator. Increasing stack height may be one option for
reducing impacts at specific receptors and will be an outcome
of permitting. For some smaller developments with combustion
sources, there is often considerable scope for optimising the stack
location and height such that dispersion is enhanced. This is an
aspect that is often neglected in the design and layout of buildings.
8.3
The presence of an AQMA should not halt all development,
but where development is permitted, the planning system should
ensure that any impacts are minimised as far as is practicable.
Even where developments are proposed outside of AQMAs, and
where pollutant concentrations are predicted to be below the
objectives/limit values, it remains important that the proposed
development incorporates good design principles and best
practice measures, as outlined in Chapter 5, and that emissions
are fully minimised.
Image: © Roger Barrowcliffe
EPUK & IAQM Land-Use Planning & Development Control: Planning For Air Quality
31
32
EPUK & IAQM u GUIDANCE
Planning For Air Quality
AADT: Annual Average Daily Traffic
AADT: Annual average daily traffic
AQA: Air quality assessment
AQAL: Air Quality Assessment Level
AQAP: Air Quality Action Plan
AQMA: Air Quality Management Area
AQO: Air Quality Objective
CHP: Combined Heat and Power (Plant)
Defra: Department for Environment, Food and Rural Affairs
EA: Environment Agency
EIA: Environmental Impact Assessment
EPR: Environmental Permitting (England and Wales) Regulations
2010
EPUK: Environmental Protection UK
EU:
European Union
EV: Electric vehicle
HDV: Heavy Duty Vehicle
HRAPIE
Health risks of air pollution in Europe – A World
Health Organisation project
IAQM: Institute of Air Quality Management
LA: Local Authority
LAQM: Local Air Quality Management
LAQM.TG(16):
Local Air Quality Management: Technical
Guidance (16)
LDF: Local Development Frameworks
LDP: Local Development Plans
LDV: Light duty vehicle
LPA: Local planning authority
NO
2
: Nitrogen dioxide
NO
x
: Oxides of nitrogen
NPPF: National Planning Policy Framework
NRW: Natural Resources Wales
PM
10
and PM
2.5
: Particulate matter with an aerodynamic
diameter of less than 10 microns (μm) (PM
10
) or less than 2.5μm
(PM
2.5
), expressed in units of μg/m
3
.
PPG: Planning Practice Guidance
PPW: Planning Policy Wales
PHE: Public Health England
SPD: Supplementary Planning Document.
SPG: Supplementary Planning Guidance.
SO
2
: Sulphur dioxide
TAN: Technical Advice Note
VPD: Vehicles per day
WG: Welsh Government
Abbreviations and acronyms
IAQM
c/o Institution of Environmental Sciences
3rd Floor, 140 London Wall, London
EC2Y 5DN
+44 (0)20 7601 1920
info@the-ies.org
www.iaqm.co.uk
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