When does the council ask for it?
The need depends on the proposal, its surroundings and local requirements. National planning guidance identifies relevant factors such as changes in traffic, sensitive uses near pollution sources and the cumulative effects of development. The local authority's air quality information and environmental health advice help establish the assessment scope. [1]
Epping Forest's published 2026 validation list includes air quality assessment requirements for relevant residential and traffic-generating proposals. Westminster also sets local submission requirements. Do not assume that a London template applies unchanged outside London, or that being outside an Air Quality Management Area automatically removes the need for assessment. [2] [3] [1]
What should the assessment cover?
The report should describe the existing conditions, the likely effects of the development and the measures proposed to avoid or reduce adverse impacts. The assessment can need to consider both construction and operation, as well as the exposure of future occupiers. Its detail should match the nature and scale of the issue. [1]
Ask the consultant to explain the information needed from the design team. This may include the proposed use, traffic assumptions, the location and specification of relevant plant, and the arrangement of occupied spaces. Keep these inputs consistent with the transport, energy and architectural submissions.
For the client, the useful output is a clear account of what needs to change or be managed. Request a summary that distinguishes design measures shown on drawings from measures that depend on later construction or operational management.
Who prepares it?
Use a specialist with relevant air quality assessment experience. Agree the scope with the planning authority where there is uncertainty about the sources, pollutants or affected locations that need investigation. National guidance recommends early engagement so the necessary evidence and mitigation can inform the design. [1]
Clarify whether the service includes construction dust assessment, operational modelling, responses to council comments and review of revised designs. These are scope questions, not a list of services every small development must purchase.
What about fine particles?
Defra's interim planning guidance on PM2.5 focuses on reducing emissions and exposure through the design process. It encourages consideration of practical mitigation early, rather than treating a comparison with an existing concentration limit as the whole assessment. The guidance remains expressly interim; it should not be described as a newly commenced building regulation. [4]
Ask the author to state how the applicable current guidance has been addressed and whether further measures are proposed. Avoid treating a general statement that the site is “within limits” as a substitute for the required assessment.
Keep the approved solution coordinated
Check the report again when changing access, plant, ventilation or the proposed use. National policy P3 addresses the development's pollution effects and the conditions experienced by its users, so the final evidence should describe the final scheme. [5]