Air quality and new developments

Impact of new developments on air quality

All developments have a potential to impact on air quality, positively as well as negatively. Therefore it is important that the potential impact of new development on air quality is taken into account in planning decisions.

The National Planning Policy Framework (NPPF) requires that planning policies and decisions should: contribute towards compliance with limit values and objectives for air pollutants; take into account the cumulative impact from individual sites in local areas; identify opportunities to improve air quality and mitigate any impacts and be consistent with the Local Air Quality Action Plan. Applications for developments should give priority to more sustainable forms of travel and be designed to enable charging for plug-in and other ultra-low emission vehicles in safe, accessible and convenient locations.

Air quality impacts of developments will arise during both the construction/demolition and operational phases, and are particularly important to consider where:

  • the development is likely to generate a significant air quality impact in an area where air quality is known to be relatively poor e.g. within or adjacent to the Air Quality Management Area (AQMA)
  • the development is likely to expose people to existing sources of air pollution e.g. if the development is located in an area of poor air quality or the AQMA
  • the development itself could lead to an exceedance of an air quality objective and result in a requirement to designate an AQMA
  • granting planning permission is likely to adversely impact upon the implementation of air quality strategies and action plans.

Current Salford City Council planning policy EN17 - Pollution Control sets out the local approach to the relationship between planning and air quality.

Air quality assessment

An air quality assessment will consider the air pollution emission sources of all phases (such as demolition/construction/operation) of the proposed development and the significance of any impacts. If necessary, it will propose mitigation measures to ensure that any impacts are minimised as far as is practicable and the development can proceed. The latest EPUK/IAQM guidance and DEFRA Local Air Quality Management Technical Guidance (TG16) should be used as current best practice guidance to assess and mitigate emissions, and also consider opportunities to improve air quality.

Indicative criteria for when an air quality assessment will be necessary to support a planning application is set out below.

Indicative criteria for when an air quality assessment will be necessary to support a planning application

Any development which introduces any of the following:

  • A new relevant receptor into an area of relatively poor air quality. For example, the Air Quality Management Area or an area where there is a source of odour and/or dust that may affect health and amenity for future occupants of the development (regardless of scale).
  • An activity associated with significant sources of dust or odours (such as all mineral development, waste handling construction and demolition).
  • An activity that requires an Environmental Permit.
  • Have one or more substantial combustion processes where there is a risk of impacts at relevant receptors, including combustion plant associated with standby emergency generators (typically associated with centralised energy centres), shipping, waste incineration or biomass plant.

In addition, an air quality assessment will be required if any of the indicative criteria in A below apply, together with any of the criteria in B:


  • Residential development greater than ten or more dwellings or development above 0.5 ha (site area) where the number is unknown.
  • More than 1000 m2 of floor space for all other uses or a site area greater than 1 ha.


  • The development has more than 10 parking spaces.
  • The development is likely to have a significant change in traffic (significant is considered to be a change of Light duty Vehicles (<3.5T) flows of more than 100 AADT (annual average daily traffic) within or adjacent to an AQMA or more than 500 AADT elsewhere or the development is likely to have a significant change in Heavy Duty Vehicle (>3.5T) flows of more than 25 AADT within or adjacent to an AQMA or More than 100 AADT elsewhere)
  • The development will involve the realignment of roads, such as changing the proximity of receptors to traffic lanes, where the change is 5m or more and the road is within an AQMA.
  • The development will introduce a new junction or remove an existing junction near to relevant receptors.
  • Introduce or change a bus station.
  • Have an underground car park with an extraction system and more than 100 vehicle movements per day

Applicants are advised to scope any air quality assessment with Salford City Council prior to submission.

For a more definitive list please and further information on air quality assessments please refer to the latest Environmental Protection UK/ Institute of Air Quality Management guidance on land use planning and development control.

Planning applications will be assessed against a validation checklist to determine whether a supporting air quality assessment is required, which is in line with the guidance.

COVID and Air Quality Assessments

Salford City Council’s monitoring data for 2020 shows a significant reduction in annual mean nitrogen dioxide (NO2) concentrations compared to previous recent years, due to reduced traffic emissions resulting from social distancing restrictions.

As part of the air quality assessment process it is standard practice to verify an atmospheric dispersion model against local monitoring data, to improve its reliability in a local context. Extreme care should therefore be taken if using 2020 monitoring data for this verification, to avoid underestimating pollutant concentrations and impacts. Additional sensitivity tests may be required to explore the constraints of using this data in terms of background concentrations and pollutant contribution from road sources. Further information is available from DEFRA guidance document ‘COVID-19: Supplementary Guidance’.

Mitigation measures

Examples of mitigation measures that might be considered include the following:

  • Designing the internal layout so habitable rooms are removed from the pollutant source
  • Traffic reduction and / or management measures
  • Robust travel plans aimed at encouraging modal shift to low carbon sustainable travel modes
  • Financial incentives for walking, cycling and public transport
  • Incentivisation for low emission vehicles such as charging facilities or electric vehicle car clubs in apartments
  • Measures to control dust emissions from demolition, earthworks, construction and trackout activities

Preference should be given to measures that prevent emissions or avoid exposure/impacts to the pollutant by eliminating or isolating potential sources or by replacing sources or activities with alternatives.

For major developments, particularly those in areas where there is the cumulative impact from several developments or where a significant air quality impact is likely, a damage cost calculation may be required as part of the air quality assessment. Damage Costs are an estimation of the economic impact caused by the increased emissions of nitrogen dioxide (NO2) and particulates from the new development. Further information on calculating Damage Costs is available from DEFRA and the EPUK/IAQM guidance (PDF). The final damage costs can then be used to determine a proportionate contribution, or provision of, additional mitigation on site. Where on site mitigation is not possible off site measures may need to be considered. 

It is recommended that developers intending to submit plans that may have a significant impact on air quality (or any proposals for non-gas fuelled heating systems such as biomass or CHP) contact the local planning authority at the pre-application stage to discuss their proposals. Every effort should be made to obtain agreement with the planning authority on the appropriate datasets and methodologies to be used for air quality assessments.

This page was last updated on 5 May 2021

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