Air Quality SPD

1. Introduction
Hoare Lea has been instructed by Barwood Land to provide comments on the Consultation Draft Air Quality &
Planning Supplementary Planning Document (SPD), issued by Warwick District Council (WDC) on 5 September
2018.
2. Background
WDC has a duty to review and assess air quality within the district. Nitrogen dioxide (NO2) is measured at 56
locations, particulate matter (both PM10 and PM2.5) at two locations and benzene at one. The national air
quality objectives are achieved for all pollutants except NO2. Annual mean concentrations of NO2 have
exceeded the objective for many years, and appear to be increasing in some locations, mainly due to emissions
from road transport.
The WDC have declared five Air Quality Management Areas (AQMAs) due to high concentrations of NO2. These
are in Warwick, Leamington Spa and Kenilworth.
While the PM objectives are not exceeded there is no threshold below which health effects do not occur. The
objectives are significantly higher than the World Health Organization's guideline values (two times higher for
PM10 and at two and a half times higher for PM2.5) and therefore reducing concentrations of these pollutants is
also important to protect public health.
In April 2014 WDC produced a 'Low Emission Strategy Guidance for Developers' which sets out a three-stage
process to assessing the air quality impacts of development proposals and identifying appropriate mitigation
measures. The Air Quality & Planning SPD will replace this document.
An Air Quality Action Plan setting out the measures WDC intends to take to improve air quality was published
in 2015. It includes a specific action on using the planning system to improve local air quality.
In September 2017 the Council adopted the Warwick District Local Plan 2011-2029. There is no specific air
quality policy in the plan. As road traffic is the major source of poor air quality in the District it is included in
Policy TR2 on traffic generation. This policy includes the following text:
"Any development that results in significant negative impacts on air quality within identified Air QualityManagement Areas or on the health and wellbeing of people in the area as a result of pollution should
be supported by an air quality assessment and, where necessary, a mitigation plan to demonstrate
practical and effective measures to be taken to avoid the adverse impacts"; and
"All measures required in the policy should take full account of the cumulative impact of all development
proposed in this Plan (and any other known developments) on traffic generation and air quality."
Policy TR1 on access and choice also includes the following requirement:
"d) where practical, incorporate facilities for charging plug-in and other ultra-low emission vehicles were
the development proposals include provision for off street parking and is for one or more dwelling".
The rationale given for these policies in the Local Plan is that large development has the potential to add a
significant number of road vehicles onto the transport network. Unless this is addressed, it is likely to have a
negative impact on air quality in general and specifically within the AQMAs, either through the generation of
additional traffic volumes or via reduced traffic speeds. Encouraging the use of ultra-low emission vehicles will
help reduce these impacts.
3. The Air Quality & Planning SPD
The SPD requires a three-stage process for the assessment of air quality (draft SPD page 23):
1. Determining the classification of the development proposal;
2. Assessing and quantifying the impact on local air quality; and
3. Determining the level of a mitigation required by the proposal to make the scheme acceptable.
4. Stage 1 - Classification of development proposals (draft SPD pages 24-23
Table 1 (page 23) sets out the classification system for minor, medium and major development. For all classes
an assessment of the exposure to poor air quality of future users of the development is required. Table 1
would be clearer if it explicitly says whether a) an exposure assessment is required; and b) an air quality impact
assessment is required by having two separate rows in the Table.
The need for an exposure assessment is consistent with the National Planning Policy Framework (NPPF)
(paragraph 170 e) requires the planning system to prevent new development being put at unacceptable risk
from air pollution).
The quantification of the impacts is only required for major developments. These are defined as developments
which:
1. are required to have a Transport Assessment or Travel Plan and
2. are within or adjacent to ad AQMA or Clean Air Zone (CAZ)1, or
3. is an Environmental Impact Assessment (EIA) development and air quality is included; or
4. meet the criteria in Table 2 of the SPD (i.e. there may be a material impact).
EIAs are only required to include significant effects. If none of the criteria in Table 2 are met there will be no
significant impact on air quality and therefore an air quality assessment would be scoped out of the EIA.
Therefore item three in the list on page 23 is redundant and should be deleted.
Table 2 of the SPD (page 24) provides a very comprehensive list of 14 additional criteria that would trigger the
need for an air quality impact assessment. There is duplication of requirements. Table 1 below provides comments on each criterion. Some of them are based on old non-statutory guidance and may no longer be
relevant.
The source of criteria has been identified where possible. In the table EPUK is Environmental Protection UK
and IAQM is the Institute of Air Quality Management. These organisations produced non statutory guidance
'Land-Use Planning & Development Control: Planning For Air Quality in 2015, which was last updated in 2017.
EPUK also produced guidance in 2010 which drew on 2008 IAQM guidance. The 2010 EPUK document was
replace by the 2015 joint guidance.
Table 1: Criteria for an Air Quality Impact Assessment
Table 2 of the SPD criteria Source2 Comment
1 Proposals in areas where sustained compliance
with EU Limit Values may be at risk
NPPF Required
2 Any development proposing a net increase of 100
or more parking spaces
2010 EPUK
guidance
Impact depends on the
number of movements
(short term car park will
have a greater impact than a
long term car park)
3 Any development that could increase the existing
traffic flows on roads of > 10,000
AADT by 5% or more
2010
EPUK
guidance
This duplicates criterion 4 -
recommend deletion
4 Any development that causes a change in LDV (cars
and small vans) flows of:
- more than 100 AADT within or adjacent to an
AQMA, CAZ or exceedance area
- more than 500 AADT elsewhere
EPUK/
IAQM
guidance
Required
5 Any developments that could increase traffic flows
by 5% or more in road canyons (or creates a
canyon) with > 5,000 AADT
2010 EPUK
guidance
Unlikely to be an air quality
issue in a street canyon with
less than 5,000 AADT.
6 Any development that causes a change in HDV
flows (lorries, large vans and buses) of:
- more than 25 AADT within or adjacent to an
AQMA, CAZ or exceedance area
- more than 100 AADT elsewhere
EPUK/
IAQM
guidance
Required
7 Proposals that could introduce or significantly alter
congestion (DfT Congestion) and includes the
introduction of substantial road infrastructure
changes
Replaced
2010 EPUK
guidance
It is unclear what 'DfT
congestion' means.
This is too woolly to be
useful, and does not add to
existing guidance.
Regarding infrastructure
EPUK/IAQM has criteria of
'where the change is 5m or
more in and the road is
within an AQMA' and
'Applies to junctions that
cause traffic to significantly
change vehicle accelerate/
decelerate, e.g. traffic lights,
Table 2 of the SPD criteria Source2 Comment
or roundabouts."
8 Proposals that reduce average speeds by more
than 10 km per hour
Highways
England
Speed data is rarely
available from transport
assessments, and its
importance depends on
what the existing speed is.
Could increase or reduce
emissions depending on the
circumstances.
Delete
9 Proposals that include additional HGV movements
by more than 10% of total trips
? This is covered by criterion
6
10 The construction, widening or repositioning of a
road in the vicinity of sensitive receptors
? This is too woolly to be
useful. See comment to
criterion 7.
11 Where significant demolition and construction
works are proposed
? The impact of construction
traffic is covered by criterion
6. All medium and major
development should have a
construction dust risk
assessment to identify
appropriate dust mitigation
measures
12 Where a centralised combustion unit of thermal
input >300kWh is proposed
? Unclear why a 300 kWh
threshold has been used.
13 All biomass boiler and other large novel fuel
appliance applications
? Required as biomass boilers
have higher emissions that
gas boilers.
14 All stand-by/short-term power generation units
regulated by the Environment Agency
? Required to ensure that the
site is suitable for the
proposed development
The EPUK/IAQM non statutory guidance is very widely relied upon by both air quality consultants and air
quality officers in local authorities. It is well understood by the profession and was produced by a working
group comprising of local authority officers and air quality consultants. It was consulted on prior to its
publication and is regularly updated.
It is not clear why WDC believe they need a bespoke set of criteria. Pollution levels are not abnormally high in
the District. Unless there are special circumstances in Warwick District it is recommended that this table is
deleted and replaced with reference to the EPUK/IAQM guidance.
For example, the SPD could say: "For all major development should consider the need for a detailed air quality
assessment using the criteria in the latest version of the EPUK/IAQM guidance. The developer or agent will
need to submit to the local planning authority either a compliant air quality assessment or the reasons why
they consider one is not required.".
It is good practice to consult with local authority to agree the scope and method of assessment prior to
commencing the work. This is the opportunity for the local authority to raise any local issues that may require
a non-standard approach or an assessment where normally one would not be required.
5. Stage 2 - Air Quality Impact Assessment (SPD pages 24-26)
5.1 Minor and medium development (SPD page 24)
For minor and medium developments an assessment of exposure of future users of the proposed development
to poor air quality is required. This is a reasonable requirement for development where users may be exposed
over the relevant averaging period of the objective. Statutory guidance provides examples of where the air
quality objectives apply3. It is normal practice to assess exposure against the national air quality objectives. It
would be useful if this is included in the final SPD.
If the District Council intends to use a lower value with respect to PM it should say so, and justify its choice. It
should be noted that there is good evidence that the direct (exhaust) emissions of PM from road vehicle fitted
with diesel particle filters (DPFs) are extremely low. This technology has been installed in new vehicles for a
number of years, and as the fleet turns over the exhaust emissions of PM for traffic will continue to decline.
The draft SPD requires an exposure assessment within 20 metres of roads highlighted on Defra's GIS model or
roads with more than 10,000 AADT. The Defra GIS map does not show any exceedences of the objective in
Warwick District. The air quality objective will not be exceeded alongside the vast majority of roads that meet
this criterion in rural areas where background concentrations are low. Even in urban area many roads with
traffic flows greater than 10,000 AADT will not exceed the air quality objective. Therefore this requirement will
require a large number of unnecessary assessments to be undertaken.
The local authority has, as mentioned earlier, a statutory duty to review and assess air quality in its district.
This duty was introduced over 20 years again, and therefore the local authority should have a very good idea of
where air quality is poor. The need for an exposure assessment should be limited to the AQAMs and where
monitoring shows that NO2 concentrations are close to the objective.
For example, the SPD could state "An exposure assessment is required where new development is in an AQMA
or annual average concentrations of greater than 98% or more of the air quality objective have been
measured".
It is reasonable to refuse planning consent if no suitable mitigation measures are proposed where there is a risk
of users of the development being exposed to concentrations exceeding an air quality objective.
5.2 Major development (SPD page 38-39 and Appendix 2)
The SPD requires a detailed air quality assessment to determine the impact on public health and the local
environment. This should meet the requirements of the most recent version of LAQM.TG16 and Appendix 2 of
the SPD. It does not mention the exposure assessment (or health exposure test as it is termed in Figure 1). It
would be useful to reiterate that it is required in this section. It is too easy to classify a development as major
and then only read the text under the Major Classified Proposals heading.
The SPD directs the reader to a website (www.warwickdc.gov.uk/info2050/pollution) for further details of the
air quality assessment requirements. This website does not provide further detail of the requirements.
The SPD requires a calculation of the pollutant damage costs to "consider the appropriate scale and kind of
mitigation that is required to make major development acceptable in terms of air quality". The appropriateness
of this approach is discussed in the next section on mitigation.
The SDP states "Should there be no net increase in trips arising from a development scheme then the damage
costs are zero". This ignores the emissions from any centralised boiler that might be part of the proposed
development. This should be re-phrased to make it clear it only relates the transport emissions.
Appendix 2 states (emphasis added) "An air quality assessment should clearly establish the likely change in
pollutant concentrations at relevant receptors resulting from the proposed development during both the
construction and operational phases. It must take into account the cumulative air quality impacts of committed
developments (i.e. those with planning permission)."
It is not possible to quantify the impact of construction on pollutant concentrations. Indeed Appendix 2 of the
SPD (page 38) states that modelling is not appropriate for this type of assessment. This requirement to "clearly
establish the likely change in pollutant concentrations" for the construction phase should be deleted from the
SPD.
It would be useful for there to be a paragraph on the requirements for an assessment of the impact of the
demolition and construction phases in the main part of the assessment. It is currently in Appendix 2 (Page 38).
In this appendix the relevant IAQM guidance is wrongly referenced. It should be 'Guidance on the assessment
of dust from demolition and construction'4. This uses a risk based approach with the aim of identifying the
most appropriate mitigating measures commiserate with the risk.
For the operational impacts (Appendix 2 page 36) it is reasonable to require dispersion modelling to assess the
impact of the emissions associated traffic on local air quality in most, but not in all, cases. There may be some
situations where a qualitative assessment is adequate, for example where monitoring data shows that the
objectives are achieved by a wide margin. It is therefore suggested that the word 'generally' is inserted before
'require' in the following sentence: "The assessment will require dispersion modelling utilising agreed
monitoring data, traffic data and meteorological data."
The key components of the Air Quality Assessment (Appendix 2 page 36) are appropriate. It should be
recognised, however, that the prediction of the impact of a proposed development with mitigation measures
(point 4.) will require assumptions to be made where there is little empirical evidence. For example the
provision of electric vehicle charging points will encourage people to use electric vehicles, but we are not
aware of data relating the provision of charging points, for example in new residential developments and the
use of electric vehicles.
The SPD (Appendix 2 page 37, third line) requires a modelling sensitivity test to be undertaken assuming that
future emissions may not reduce. There is good evidence that the latest generation of diesel vehicles have
lower NOx emissions than earlier generations, and that DPFs are very effective at reducing exhaust PM
emissions. Therefore it is reasonable to expect vehicle emissions per kilometre driven to decline in the future.
The approach taken to the sensitivity test should take into account how far ahead the assessment year is. If
only one or two years ahead it is reasonable to use the same emissions per vehicle kilometre as in the base
year for the sensitivity test. For an assessment year, say, ten years ahead this approach will significantly overestimate
future air quality, and may result in unnecessary and potentially costly, mitigation measures being
installed. Therefore the guidance should not be prescriptive.
6. Stage 3 - Mitigation (SPD pages 27-32)
The introduction to this section quotes from paragraph 152 of 2012 NPPF; paragraph 32 of the 2018 NPPF is
similar. It states "Where significant adverse impacts are unavoidable, suitable mitigation measures should be
proposed (or, where this is not possible, compensatory measures should be considered).
6.1 Construction phase (draft SPD Tables 3 and 6 page 29)
For the construction phase medium and major developments are required to meet specified emission
standards for non-road mobile machinery. The standards recommended in Table 6, are not the most recent,
and are considered to be reasonable.
A Construction Environmental Management Plan (CEMP) is required to be submitted and agreed with the
Council officers for medium and major development (see Table 3). It would be clearer if this requirement was
for a Dust Management Plan (DMP) including appropriate mitigation measures identified in the construction
assessment. The DMP could be incorporated into a Construction Environmental Management Plan.
The mitigation section would be clearer if all the requirements for the construction phase where grouped
together. It is confusing that Table 3 for Type 1 developments, i.e. minor developments, includes construction
phase mitigation measures that only apply to medium and major developments.
Whilst the SPD provides details of many mitigation measures for the operational phase, only one (on non-road
mobile machinery) is provided for the construction phase. Was this imbalance intended?
6.2 Operational phase (draft SPD, Tables 3 to 5, pages 27 to 29)
The SPD requires developers to produce a mitigation statement setting out the mitigation/compensation
measures to be adopted which must be equal in value to the damage cost calculated as part of the assessment
(page 27).
This approach assumes that the cost of mitigation or compensation measures is equal to the damage cost. This
is not the case as the damage cost is based on emissions not local air quality. One tonne of emissions of a
pollutant will have a very different impact on air quality depending on where it is emitted.
The mitigation (and compensation) measures should be aimed at the reducing the impact to make the
development acceptable in air quality terms. There have been two recent High Court judgements where
developers have lost their appeals because they failed to demonstrate that the mitigation measures would be
effective at reducing the impacts.
This approach of using the damage cost calculator to determine the amount of mitigation has been adopted by
a small number of local authorities. Whilst we are not aware of any appeals relating to its use, there is
increasing litigation regarding air quality in the Courts, often brought by residents groups opposing new
development. There is a risk therefore, that this approach may be challenged in the future. It is recommended
that it is not used to identify the mitigation measures.
Mitigation measures should be identified for a development taking into account the predicted impact of the
development on local air quality, and the likely impact of the mitigation measure.
The SPD gives examples of mitigation measures are presented for each type of development. It would be
useful at the start of each Table to make it clear that for Type 1 development only Table 3 applied, for Type 2
developments both table 3 and 4 apply, and for Type 3 developments Tables 3. 4 and 5 all apply. Although this
is stated in the text surrounding the tables, readers may miss it.
Type 1 Mitigation (Table 3) Minor Development
This sets out the requirements for electric vehicle charging points for residential, commercial/retail and
industrial developments. For example, this requires one charging point for dwelling with dedicated parking or
one charging pointer per 10 spaces.
Type 2 Mitigation (Table 4) Medium Development
Most of the measures in this table are transport measures designed to support the use of monitored transport
plans, public transport, cycling and walking. The only mitigation measures directly addressing air quality are
those that encourage the use of low emission and electric vehicles. It should be made clear that the same
transport measures can be used to mitigate transport and air quality impacts.
Type 3 Mitigation (Table 5) Major Development
The measures in Table 5 are under a heading "off-set mitigation". It is unclear what these means in this
context. If it is a financial contribution t is important given the recent judicial Reviews that the measures are
directly related to the impacts of development. A financial contribution for example, to an 'Air Quality
Monitoring Programme' is not mitigation. The local authority has a statutory duty to review and assess air, and
new development should not be used to support a local authority's statutory duties.
5.5 Specific issues
The draft SPD includes minimum standards for heating plant. These are the same as used in the 2014 London
supplementary Planning Guidance on Sustainable Design & Construction.
5.53 Standby/ backup power generation
It would be useful to include a statement that the air quality assessment should consider both the long term
and short term impacts, and that the assessment should use the maximum number of hours per year that it will
operate. Consideration should be given to including a condition to the planning permission restricting
operation to the number of operational hours included in the assessment.
5.55 Mechanical ventilation
This section is too prescriptive requiring sensitive development, to be at least 20m from the kerb, with the
arrangement of living space to afford separation from a pollutant source. This is again too prescriptive. This
should only apply where an air quality objective is predicted to be exceeded. The use of mechanical ventilation
to protect users of a development should not be dismissed out of hand. In the planning balance it might be
better to have housing with mechanical ventilation than no housing.
7. Recommendations
The following changes are recommended:
1. Chapter 5 on Development Classification, Assessment and Mitigation is overly complex and should be
simplified. Consistent terminology should be used in the text and Figure 1, and the construction and
operation phases considered separately.
2. Table 1 - reference to EIA should be deleted.
3. Table 1 0 have two separate rows exposure assessment (i.e. the impact of traffic emissions on the
development) and impact assessment (i.e. the impact of the proposed development on existing receptors).
4. Table 2 should be deleted (unless Warwick District has abnormal air quality) and replaced with "For all
major developments developers should consider the need for a detailed air quality assessment using the
criteria in the latest version of the EPUK/IAQM guidance. The developer or agent will need to submit to
the local planning authority either a compliant air quality assessment or the reasons why they consider one
is not required".
5. Section 5.2 MINOR and MEDIUM Classified Proposals - should clearly state that the criteria for assessing
exposure are the air quality objectives.
6. Section 5.2 Section 5.2 MINOR and MEDIUM Classified Proposals - Delete the requirement of exposure
assessment for proposed development within 20m of roads with traffic flows exceeding 10, 000 AADT and
replace with "An exposure assessment is required where new development is in an AQMA or measured
annual average concentrations of are X% or more of the objective ". The X% could be set at 98%
7. Section 5.2. MAJOR classified Proposed - this should also include a section on exposure assessment to be
consistent with Figure 1.
8. Remove the reference to further details of the air quality assessment requirements being on
www.warwickdc.gov.uk/info2050/pollution
9. Rephrase the following sentence "Should there be no net increase in trips arising from a development
scheme then the damage costs are zero" to make it clear it only relates the transport emissions, and if a
development includes a large boiler, the damage cost calculation is required (but see comment 10 which
overrides this comment).
10. Remove all references to the damage cost calculation.
11. Have a separate section on the demolition and construction phases, clearly setting out the Council's
requirements. Provide the correct title of the IAQM guidance and recommend a risk assessment based on
the source-pathway-receptor approach. Make it clear that modelling of these phases is not appropriate.
12. Appendix 2 - add some flexibility to the assessment method by saying "the assessment will generally
require dispersion modelling utilising agreed monitoring data, traffic data, and meteorological data".
13. Appendix 2 -sensitivity tests. Delete the requirement for a sensitivity test assuming that there will be no
improvement to vehicle emissions as this is unrealistic. Replace with "An appropriate sensitivity test
should be undertaken assuming that emissions do not reduce at the rate forecast by Defra's emission
factor toolkit."
14. Stage 3 - Mitigation - this section should separate the mitigation requirements for the demolition and
construction phases from the operational phase, and group them together
15. Stage 3 - Construction phase mitigation. It is suggested that the term 'Dust Management Plan' is used
which can be incorporated into a Construction Environmental Management Plan.
16. Stage 3 - Operational impact. Remove all references to damage cost calculation and to all mitigation
measures which will not reduce the air quality impact of development.
17. Stage 3 - Operational impact, Tables 4 and 5. Make it clear in the tables that medium development needs
to consider the measures in Tables 3 and 4, and major development in Tables 3, 4 and 5.
18. Stage 3 - Operational impact. Many of the measures are transport measures that will be included as part
of the development. Make it clear that these can count towards mitigating both transport and air quality
impacts.
19. Stage 3 - Operation impact. Clarify what 'off-set mitigation" means and remove all examples of measures
that has no direct role in reducing the air quality impact of development (such as a financial contribution
for monitoring).
20. Section 5.55 on mechanical ventilation. This mitigation measure should not be dismissed. There
requirement for sensitive development, to be at least 20m from the kerb, with the arrangement of living
space to afford separation from a pollutant source is too restrictive and should be deleted.