ACP insights & guidance
A PM2.5 planning assessment starts with the site layout and the activities that the proposal will introduce. In England, National Planning Policy Framework policy P3 explicitly includes fine particulate matter among the pollutants relevant to planning decisions.
Fine particles can come from several activities across a development. The question is which sources and exposure pathways matter here, and what the design team can still change.
Read policy P3 with the project in view
P3 asks decision-makers to consider pollution effects on and off site, including cumulative effects and existing conditions. It also asks proposals to sustain and contribute to compliance with relevant air pollution objectives and targets. Identify applicable Air Quality Management Areas and the objectives of relevant local plans and strategies.
Defra’s interim planning guidance, published on 4 October 2024, addresses England’s Environment Act PM2.5 targets. It asks applicants within its stated scope to identify key sources and minimise PM2.5 and precursor emissions as far as reasonably practicable. The national targets concern ambient concentration and population exposure. An individual project still needs evidence suited to its location and decision.
Separate emissions from exposure
- Construction. Identify demolition, earthworks, plant and vehicle movements. Agree dust controls, responsibilities and any monitoring with reference to the relevant guidance and site risk.
- Operation. Confirm the energy strategy, combustion equipment and traffic assumptions. Record which changes could affect emissions or their precursors.
- Exposure. Map homes, schools and other sensitive uses. Check whether people would spend time near busy roads or other sources. Include proposed dwellings and spaces within the site as well as neighbours.
- Evidence. Put the sources, receptor locations, design responses and unresolved assumptions on the same dated plan. Ask the air quality specialist what qualitative or quantitative evidence is proportionate.
An illustrative layout decision
Suppose new flats sit beside a busy road. The proposal includes a play space at the roadside edge and several ground-floor bedrooms facing the traffic. The team can compare an internal courtyard location, the position of air intakes and the relationship between building layout and exposure. Keep those choices visible in the assessment brief before fixing the design.
A quieter elevation may support an alternative ventilation strategy. Check air quality, acoustics and overheating together before relying on that change. The project record should explain which design options were tested, what changed and which residual effects still need assessment.
What to send for scoping
Share a location plan, current drawing revision, proposed land uses, construction outline, energy strategy and available transport assumptions. Flag nearby sensitive receptors and any local validation requests. If the project is in London, also check whether the separate air quality neutral benchmark process applies. Keep its evidence distinct from the assessment of exposure and wider effects.
Common question
Does a London air quality neutral assessment cover PM2.5 exposure?
The London benchmark check serves a separate purpose. Establish whether the project also needs exposure and wider air quality evidence under the applicable planning policies.
References and scope
- MHCLG, National Planning Policy Framework, Chapter 17, policy P3
- Defra, PM2.5 targets interim planning guidance, 4 October 2024
Discuss the project brief
Send the location plan and the design decisions still open for an air quality scoping discussion.