Air Quality and Planning

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					 Air Quality
and Planning

                          Air Quality and Planning

Air quality may be a material consideration in determining planning applications.
The aim of this document is to provide guidance on the way in which air quality
and air pollution issues will be dealt with through the planning system. Poor air
quality can have detrimental impacts on health and the amenity of users of land
in terms of odour, dust and nuisance. The planning system has a key role in
protecting people from unacceptable risks to their health and in providing an
adequate protection to the amenity value of land. These considerations must,
however, be balanced against other aims of the planning system such as to
secure economic regeneration and provide adequate levels of housing. The aim
is to achieve sustainable development in the borough that achieves the best
balance of social, economic and environmental considerations. All of these
considerations can have significance for both spatial policy and individual
development control decisions.

Legislative background
Under the Environment Act 1995 and associated regulations all local authorities
are required to regularly review and assess air quality in their area against the air
quality objectives (AQO’s) in the Air Quality Strategy (AQS).

If the review and assessment exercise indicates that any of the objectives are
unlikely to be met by the required date, the local authority must declare an Air
Quality Management Area (AQMA) and draw up an action plan outlining how it
intends to work towards achieving the objectives.

There are currently no AQMA’s in Basingstoke and Deane Borough Council
(BDBC). However, the council has identified certain areas of the borough where
levels of nitrogen dioxide exceed or are close to the AQO. These are referred to
as Local Air Quality Priority Areas (LAQPA). It has not been necessary to
declare an AQMA in the borough due to the absence of relevant receptors such
as residential properties.

The AQS identifies the planning system as one of the key mechanisms for
achieving improvements in UK air quality. The land use planning system
regulates the development of land, and through determining the location and
design of new developments, it can lead to long-term improvements in air quality.
Accordingly the land use planning system has a vital role to play to ensure that
the objectives of the AQS are met. Guidance with regard to the local planning

authority’s air quality responsibilities is outlined in the following regional and
national guidance:

•   RPG 9 Regional Planning Guidance for the South East (2001)
•   Draft South East Plan- Proposed Changes (October 2008)
•   PPG 6 ‘Town Centre and Retail Developments’ (1996)
•   PPS 6 ‘Planning for Town Centres’ (2005)
•   PPG 13 ‘Transport’ (2001)
•   PPG 23 ‘Planning and Pollution Control’ (1997)
•   PPS 23 ‘Planning and Pollution Control’ (2005)
•   LAQM G4(00), Air Quality and Land Use Planning

PPS 23 identifies the relationship that exists between land use planning and the
pollution control systems. Whilst PPS 23 advises that local planning authorities
should not duplicate the pollution control responsibilities of other bodies, the
planning system has an important complementary role to play. In particular
through shaping the pattern of development and influencing the location, scale,
density and mix of land uses, the planning system can influence air quality
significantly. PPG 6 and PPG 13 also address the issue of air quality, through
promoting sustainable forms of development, ie focusing development in
locations such as town centres that are well served by public transport and thus
reducing the need to travel, and the length of journeys made. PPG 13 also
emphasises the importance of well designed traffic management as a measure to
reduce air pollution (Para 45).

What is the purpose of an air quality impact assessment?

There are two kinds of impacts that must be considered:

    •   the impact the development will have on air quality, ie a development that
        increases emissions; and

    •   the impact of existing poor air quality on the development, ie a
        development that increases exposure.

Some developments will cause both types of impact, others will only cause one
and some neither.

An air quality impact assessment can, therefore, assess:

    •   Site suitability: is an area that is already exceeding AQO’s or has limits
        close to them suitable for residential development, or could it have a
        detrimental impact upon its residents?

    •   Impact of development: will the proposed development have a significant
        impact on air quality?

The air quality assessment shall demonstrate the likely changes in air quality as
a result of a proposed development and should:

    •   assess the existing air quality in the study area

    •   predict the future air quality without the development

    •   predict the future air quality with the development.

When will an air quality impact assessment be required?

Policy E1 of the Basingstoke and Deane Adopted Borough Local Plan (1996-
2011) requires, amongst other criteria, that development proposals minimise the
potential for pollution of the air.

The Town and Country Planning (Environmental Impact Assessment)
Regulations 1999 (as amended) requires that certain planning applications are
accompanied by an Environmental Statement (ES). For these applications, air
quality assessments may form part of the (ES). In addition to this requirement,
an air quality assessment would normally be expected for the following types of
development proposal:

•   Those that will result in increased congestion, a change in either traffic
    volumes, such as a change in annual average daily traffic (AADT) or peak
    traffic flows of more than ±5% or ±10%, depending on local circumstances, or
    a change in vehicle speed (of more than ±10 kph), or both, usually on a road
    with more than 10,000 AADT. This is based on the sensitivity of emission
    rates to traffic speeds and volumes, and roads below 10,000 AADT normally
    having a minimal impact on local air quality.

•   Those that would significantly alter the traffic composition, such as increase
    the proportion of HGVs in an area, for example, bus stations, HGV parks,
    increased delivery traffic.

•   Those that include new car parking, for example, more than 300 spaces or an
    increase in current parking provision by, for example, 25%, although account
    should be taken of car park turnover, such as, the difference between
    short-term and long-term parking, or new coach or lorry parks.

•   Those that would trigger Basingstoke and Deane Borough Council (BDBC)
    transport assessment criteria as set out in Appendix B of the Department of
    Transport guidance.

•   Developments located in, or which may affect, sensitive areas, for example,.
    ecological sites, or areas of poor air quality (including AQMAs), where either
    direct emissions to air occur, or where any of the preceding criteria are met.

•   Introduction of new exposure close to existing sources of air pollutants, for
    example, road traffic, industrial operations, agricultural operations.

•   Potential impacts from construction on nearby residents.

•   Introduction of an industrial activity outlined in the Environmental Permitting
    (England and Wales) Regulations 2007 that increase emissions in the

•   Developments that would significantly increase dust emissions in areas
    where people and/or commercial activities would be exposed.

This is not a definitive list and the decision as to whether an assessment is
required should be based on the physical characteristics of the proposal and/or
the changes in traffic flows.

What guidance should be followed:-

Air quality assessments should be carried out in line with the National Society for
Clean Air (NSCA) document, Development Control: Planning For Air Quality

How detailed should the air quality assessment be?

There is no single, definitive method for carrying out a detailed air quality impact
assessment, but the method must be appropriate for the development and
proportionate to the likely significance of any air quality impact that may be
presented. The process to assess the impacts can be divided into four key stages
or phases and these are summarised in Table 1.

For some developments screening models, such as those set out in the Design
Manual for Roads & Bridges, may be acceptable, provided they can be
demonstrated to work and are suitable for the urban environment. However,
where the screening method predicts that the development may have a significant
air quality impact, it will be necessary for a detailed assessment to be carried out.
Where a detailed dispersion modelling is required, developers should consult the
Environmental Protection team about the proposed modelling technique, to ensure
it is appropriate for the air quality assessment.

Table 1 – Stages of an air quality impact assessment.

Assessment                Situation
                          All assessments should include a qualitative
Stage 1 : Qualitative     risk assessment to identify the likely pollutant
risk assessment           levels with or without the scheme and the likely
                          nature of exposure, for example, short or
                          long-term with regard to the national objectives.
                          The council has published various reports on air
                          quality and these may provide valuable
                          information. The checklists in LAQM.TG(09)
                          subject to revision, can be used to discount
                          sources. All sources discounted on this basis
                          must be stated.

Stage 2: Design manual    This is available to be downloaded at
for roads and bridges
                          Its use is accepted for the assessment of
                          transport sources only, where other emission
                          sources are unlikely to make a significant
                          contribution. It cannot be used to assess short-
                          term exposure.
                          All input and output sheets must be included in
                          the report.
                          The authority may request more detailed
                          modelling depending upon the results and/or
                          the complexity of the situation.
Road transport models     There are various road transport models
                          available. It is vital that the applicant justifies
                          the use of the model prior to its use.

Stage 3 - Detailed        It may be necessary to use a detailed
Dispersion Models         dispersion model where there are a number of
                          different emission sources:
                               • where the results from the screening
                                  models are close to or higher than the
                                  national standards
                               • where the situation is complex
                               • where the authority has already
                                  undertaken dispersion modelling to a
                                  higher standard to the screening model.

 Stage 4 - Monitoring         Monitoring can be extremely useful in
                              identifying the existing levels and in validating
                              any modelled results. A minimum of three
                              month’s data is required and the data must be
                              corrected to provide a 12 month equivalent to
                              allow for any seasonal variation in air quality
                              levels. Passive diffusion tubes can be used but
                              these should be corrected for bias.

Cumulative impact of development

Development in urban areas rarely occurs in isolation. Accordingly local
authorities should ensure that an air quality assessment for any new
development takes into account the cumulative effect of other developments in
the area. These should include both committed developments, ie those
proposals that have been granted planning permission at the time the
assessment is undertaken, as well as other proposals which planning officers
consider are likely to proceed. This will ensure that a realistic scenario of air
quality in the area is presented for both the ‘baseline’ and the ‘with development’
predictions of the air quality impact of the development.

When should the air quality impact assessment be submitted?

The air quality assessment must be submitted through the planning department
ideally before a planning application is submitted or at the very latest, with the
planning application.

Assessing an air quality assessment

Once an air quality assessment has been received, it is reviewed. The council
will review whether the assessment report contains all the information required, if
an appropriate assessment has been undertaken and if the conclusions are
consistent with the assessment results. Where relevant expertise is not available
within the council, an external peer review may be needed. The council, as the
planning authority, is then informed of the significance of the air quality effects of
the development and recommendations on their acceptability and the level of
mitigation needed are made.

Assessing the significance of impacts

It is important for the local planning authority to be able to assess the significance
of any air quality issue presented by a particular proposed development to
enable proper consideration to be given to this issue during the decision making
process. There is no simple method for making this determination which covers

all situations that may arise. The local authority intends to use the methodology
developed by the National Society for Clean Air (NSCA) in their publication
‘Development Control: Planning for Air Quality’ in assessing significance. The
significance of impacts is assessed using a series of closed questions in a
flow-chart which is shown in Figure 1. The impact significance from the
flow- chart is then linked to recommendations in Table 2.

It is important to note that the process is repetitive and that ultimately the
decision making will depend upon the extent to which a developer is able to
design out or mitigate the air quality issues. Where air quality is likely to be of at
least a medium priority significance, to avoid delays to the determination of a
planning application, pre-application discussions are essential.

       Figure 1

       Steps for local authority to assess the significance of air quality impacts of a
       development proposal
                                                   Effect of development                              Outcome

     Assemble the air quality      THEY:       Lead to a breach or
     impacts (from Air Quality
                                               significant(1) worsening of a
     Assessment)                                                                     YES         AQ an overriding
                                               breach of an EU Limit Value?
                                               This could include introduction                    consideration
                                               of new exposure to cause a


                                              Lead to a breach or significant(1)
                                                                                     YES         AQ a high priority
                                              worsening of a breach of an AQ
                                              Objective, or cause a new AQMA                       consideration
                                              to be declared(2)?


                                               Interfere significantly(1) with or
                                                                                     YES         AQ a high priority
                                               prevent the implementation of
                                               actions within an AQ action
                                               Interfere significantly(1) with the   YES       AQ a medium priority
                                               implementation of a local AQ                        consideration


                                               Lead to a significant(1) increase
                                                                                     YES       AQ a medium priority
                                               in emissions, degradation in air
                                               quality or increase in exposure,                    consideration
                                               below the level of a breach of
                                               an AQ Objective?

                                                                 NO                              AQ a low priority
                         Request additional mitigation

                                                         YES              Are mitigation measures,
                             Reach decision                               where required, adequate?

     (1) Where the term significant is used, it will be based on the professional judgement of the Local Authority Officer.
     (2) This could include the expansion of an existing AQMA or introduction of new exposure to cause a new AQMA to be declared

Table 2

 Significance Action necessary by developer                     Outcome

 Overriding     Developer must normally redesign or             Normally refuse
                where this is not possible, introduce           where impact
                measures to mitigate the impact of poor         remains overriding
                air quality.
 High           Developer normally must redesign.               May refuse where
                Where this is not possible measures to          the impact remains
                mitigate the impact of poor air quality         high
                should be included. Measures to offset
                any air quality issues should be included

 Medium         Developer should redesign if possible or        May refuse if
                develop measures to mitigate the effects        additional
                of the deterioration in air quality as far as   measures have not
                possible. Inclusion of measures to offset       reasonably been
                any air quality issues should be included.      included

 Low            Developer may redesign or mitigate any          Application would
                impacts.                                        proceed as normal

What measures can be taken to reduce the air quality impact to an
acceptable level?

Developers are encouraged to formulate proposals which will minimise additional
air pollution and preserve or enhance the existing air quality in the borough to
provide the highest quality environment for people to live and work.

Where a development is deemed to have a significant impact on air quality the
local authority will make recommendations based on the assessment results. It
is not the case that all developments where air quality is a significant
consideration, are refused planning permission. Instead the local authority will
require the developer to demonstrate that they have taken air quality issues into
account and work closely with the developer to ensure that the development has
a beneficial impact on the environment. In doing so a hierarchy of control should
be followed:




Where redesign cannot reasonably reduce the significance of the air quality
issue, it may be acceptable to include measures to mitigate, as far as possible,
air quality issues that arise. These measures should not be considered as an
alternative option to fundamental redesign but as a fall-back position.

Mitigation will still result in a significant air quality impact remaining, therefore,
additional measures to offset the potential consequence of a development should
also be considered. Where it is not possible to design out any air quality impacts,
mitigation and offsetting measures proposed will influence the ultimate planning
decision. The decision will balance the residual significance against any other
economic, social or environmental objectives of the local planning authority.

The council accepts that in some cases it may not be possible, or desirable, to
redesign a scheme for new sensitive development to reduce the air quality
impacts to a moderate or low significance. This is particularly likely to be the
case with small infill developments, where existing sensitive uses are immediate
to neighbours and the development is in no worse a position than the
neighbouring uses. In these cases the focus may be on mitigation and offsetting.
However, mitigation based on sealed and artificially ventilated building designs
are not considered a desirable option and will only be accepted as a last resort.

Where future occupants might be exposed to high levels of air pollution it is
expected that the applicants will design acceptable solutions by considering in
particular, site and internal layout. The aim should be to ensure that sensitive
façades are a suitable distance from pollution sources such as busy roads. For
mixed-use sites, generally sensitive uses should be placed in the least polluted
parts of the site. This may result in sensitive uses being located at greater
horizontal or vertical distances from busy roads. For such sites the council is
unlikely to support residential developments that rely on artificially ventilated and
sealed buildings to protect the occupants. This is because sealed residential
buildings that cannot be naturally ventilated are not desirable or sustainable.

Any proposed engineering measures, must be presented at the application stage
as a sufficiently mature design to allow the council to assess its adequacy.
Appendix 2 sets out some principles of good design and measures that can be
used to mitigate and offset against air quality impacts. The list is not
comprehensive and developers are encouraged to explore innovative measures.

Planning conditions and Section 106 Agreements.

Any agreed design, mitigation and offsetting measures will be secured through
planning conditions and/or Section 106 planning obligations. Section 106
agreements can also be secured to require the developer to provide appropriate

funds for any reasonable measure that can help the local authority improve air

What will happen if the air quality impact cannot be reduced to an
acceptable level?

In the event that mitigation cannot resolve all air quality concerns, the council will
decide whether any remaining adverse effects are sufficiently outweighed by the
social, economic or other benefits of the development to the area. In doing this, it
will consider national, regional and local development and environmental policies
and priorities as set out in planning policy guidance, regional planning guidance,
and any relevant supplementary planning guidance.

Where can I find more information?

 Area                           Relevant Information
 Planning policy                Forward Planning team
                                Tel. 01256 844844

 Development Control            Development Control team
                                Tel. 01256 844844
 Air quality                    Environmental Protection team
                                Tel: 01256 844844

Appendix 1: Reporting requirements for air quality assessment.

Requirement           Description
Introduction/scope    This should state why the assessment is being carried out and
                      provide details of the proposed development, a description and map
                      of the site.

Qualitative risk      This should set out the pollutants tand the sources of emissions to
assessment            be assessed, the location of receptors or the area for contour
                      modelling to be used, the assessment year(s) and the values
                      against which the results will be assessed.

Ambient/background The national emissions inventory allows background emissions to
levels             be downloaded on a 1km grid square via:

                      These, however, tend to be higher than locally monitored
                      concentrations. The applicant must state clearly which values have
                      been used. Care should also be taken to avoid any element of
                      double counting, ie the inclusion of the background level.

Model description     The choice of model should be justified and a description given.
                      Models that could be used include:
                         - AAQuIRE
                         - ADMS-Urban
                         - CALINE
                         - INDIC AirViro
                         - PAL
Meteorological data   Meteorological data should be taken from an appropriate site (within
                      a reasonable distance of the area to be modelled, and within similar
                      topography),At least one year of hourly sequential data should be

                      The developer should agree in advance with the Environmental
                      Protection team whether, ’typical’ or ’worst case’ meteorological
                      data are to be used.

Emission sources      The assessment must consider all relevant emission sources. This
                      must include any approved developments yet to be built, which have
                      the potential to either affect ambient air quality levels or to introduce
                      sensitive receptor types. Any cumulative impact must be

Traffic data          Detail traffic data to be used, including how and when collected.

Industrial Sources    Any assessment of a new industrial site under the planning regime
                      must clearly state the operating conditions that have been assumed
                      for example, fuel types and loading and state whether building wake
                      algorithms have been used1
The modelled area   The grid size used within the model must be clearly stated. This
                    should typically be in the region of 5 to 10m next to roads. Relevant
                    sensitive receptors should be identified and agreed with the
                    Environmental Protection team.

NOx to NO2          The conversion methodology can affect the results due to the
Conversion          uncertainty over the percentage of primary NO2 and the effect of
                    ozone. Despite these limitations, the approach detailed in
                    LAQM.TG(03) is still appropriate (as amended by the January 2006

                    The limitations of the conversion methodology should be fully
                    accounted for within the reporting.

PM10                Any PM10 modelling study should present results as a gravimetric
                    equivalent and include secondary and coarse components.

Assessment of       The key concern with regard to assessing air quality is its impact on
impacts             human health. The assessment shall consider whether the
                    development will create new areas of exposure.

                    The report must clearly state in tabular form the predicted levels at
                    the receptors with and without development scenarios. This should
                    allow easy comparison between the scenarios and concentrations to
                    be stated. The findings of the assessment must take account of any
                    uncertainties and the level of these must be clearly stated. Any
                    correction values used, for example, year conversions must be

Validation          It is important to validate the results to identify the degree of
                    modelling uncertainty, which should be applied to the results. The
                    developer should agree with the Environmental Protection team the
                    evidence of model performance to be provided, for example,
                    previous studies or new site specific validation exercise.

                    The developer must demonstrate the model’s effectiveness at
                    predicting statistics relevant to the air quality objectives.

                    Model verification and adjustment should be carried out in
                    accordance with the guidance in LAQM.TG(03) taking local
                    monitoring data into account.

Audit trail         The assessment must provide a transparent account of the
                    modelling undertaken and all assumptions made.

It should be noted that this is not an exhaustive list but is intended as a guide, other
factors may arise during discussion with the Environmental Protection team which will
require consideration.

 It is strongly recommended that the advice of the relevant permitting authority is sought where
Appendix 2 – Examples of good design, mitigation and offsetting measures

Polluting development


•   Increasing the distance between any significant pollution source and existing
    sensitive uses.

•   For larger or mixed use sites, arrange site layout to ensure sensitive and polluting
    development is adequately separated.

•   Ensure that the development design allows for the effective dispersion of

•   Ensure high emission sources are not compromised by tall sensitive buildings.

•   For large developments carefully consider the best location for car parks and
    busy access roads.

•   Ensure car park control systems minimise queuing in entry or exit and car parks
    have well designed circulation patterns.

•   In mixed use schemes consider provision of car free areas.

•   Design commercial or industrial premises to allow for 24 hour servicing.

•   Consider the impact of the development on the wider road network.


•   Positively encourage the use of public transport and low emission transport and
    commit to monitoring air pollution through a transport management strategy, for
    example. green travel plan.

•   Minimise the need for travel.


•   Provide a contribution to allow improvements in traffic management systems to
    reduce congestion, such as re-routing traffic.

•   Provide a contribution to allow changes in road design, e.g. increasing kerb
    width, one way systems, changed speed limits and improved signing

•   Provide a contribution to allow development of improved public transport,
    and facilities to encourage cycling and walking.
Sensitive development

Redesign of scheme

Factors to consider here include:

•   Increasing the distance between the development façade and the pollution source.

•   For larger or mixed use sites, arrange site layout to ensure sensitive development
    is not within the areas of poorest air quality.

•   Place sensitive uses at higher storeys only. There is no precise way of
    determining for any development site what an acceptable height is, a
    precautionary approach should be taken. It is important to ensure that uses at
    lower storeys are compatible with sensitive uses.

•   Internal arrangement to position non-habitable rooms on polluted façades.

•   Avoid features encouraging residents to spend significant periods of time in
    polluted external environments, for example, balconies.

•   Where integral car parks are proposed sufficient distance must exist between
    residential uses and ventilation systems. This may require detailed assessment.

•   Provision of car free areas.


In some cases, fixed (unopenable) glazing with system for suitable artificial ventilation.
Development that relies upon these measures is undesirable and will only be
accepted as a last resort. Suitable ventilation systems will need to:

•   take air from a clean location
•   be designed to minimise energy usage
•   be sufficient to prevent summer overheating
•   have robust arrangements for maintenance
•   be designed to ensure satisfactory internal acoustics and prevent loss of amenity
    to neighbouring uses
•   avoid providing external doors opening directly into habitable rooms on polluted


•   Providing on and off-site measures to encourage and facilitate cycling, including
    well designed, secure cycle stores and improved cycle routes.

•   Provide a contribution to improve bus services, bus stops or facilities.
•   Provide a contribution to allow new or improved traffic management measures, for
    example, improved signalling and signing.

•   Commit to establishing and funding car club.

•   Provide a contribution to allow footways to be widened.
                             Reference and Guidance Notes

•   NSCA - Development Control: Planning for Air Quality (Guidance from NSCA on
    dealing with air quality concerns within the development control process) NSCA

•   The Air Quality Strategy for England, Scotland, Wales and Northern Ireland 2007.

•   Circular 11/95 Use of conditions in planning permission. ODPM. 1995.

•   LAQM.PG (03) Policy Guidance (code PB7516), Defra 2003.

•   LAQM.TG (03) Technical Guidance (code PB7514), Defra 2003.

•   Town & Country Planning [Environmental Impact Assessments] England & Wales
    Regulations 1999.

•   PPG4 Industrial and Commercial Development and Small Firms (ISBN 0 11
    752723 8), DOE 1992.

•   PPS6: Planning for Town Centres (March 2005).

•   RPG9 Regional Planning Guidance for the South East (2001).

•   Draft South East Plan.

•   PPS11: Regional Spatial Strategies (September 2004).

•   PPS12: Local Spatial Planning – (June 2008).

•   PPG13 Transport (April 2001).

•   Planning Obligations Circular 05/2005, ODPM 2005.

•   PPS23 Planning and Pollution Control (ISBN 0117539317), ODPM 2004.

•   Basingstoke and Deane Borough Adopted Local Plan (1996-2011).
                           Sources of Further Information

Basingstoke and Deane Borough Council website this
provides links to:

   •   current information on air quality in the borough

   •   Location of existing prescribed processes

DEFRA website, contains information on air quality and
prescribed processes.

University of West of England
links to information on air quality and planning.

UK Air Quality Archive,
links to tools to assist consultants with Air Quality Impact assessments.

Planning Portal, links to advice on planning
legislation and policy.

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