An air quality assessment is required for a planning application when the development could worsen local air quality, or when it would introduce new people into an area where air quality is already poor. Most applications are screened out quickly — the skill is knowing which side of the line your site falls on before the council tells you.
This guide explains the screening approach used across the UK, based on the EPUK/IAQM Planning for Air Quality guidance that most local planning authorities follow.
When is an air quality assessment required? The two questions that decide it
Screening always comes back to two questions:
- Impact: will the development change pollutant concentrations — through the traffic it generates, its car parking, or plant such as boilers, CHP or generators?
- Exposure: will it introduce new sensitive receptors — homes, schools, care accommodation — into a location with elevated NO₂ or particulate concentrations, such as an Air Quality Management Area (AQMA) or a busy road corridor?
If the answer to both is no, a short statement recording the screening exercise is usually all the council needs. If either answer is yes, some level of assessment follows.
The triggers that usually require an assessment
The EPUK/IAQM guidance sets out indicative criteria — deliberately precautionary — for when an air quality assessment is likely to be needed. In practice, expect your local planning authority to ask for one where a proposal involves:
- A site in or next to an AQMA. Even modest residential schemes are commonly asked for an assessment where they sit inside a declared AQMA. Check your site in seconds with our free AQMA postcode checker.
- New exposure close to busy roads. New dwellings fronting congested corridors can trigger an exposure assessment even where the scheme itself adds little traffic.
- A significant change in traffic. Material increases in vehicle movements — especially HGVs — on roads near sensitive receptors are a classic trigger; the thresholds are lower inside an AQMA.
- Substantial car parking. Large new car parks concentrate emissions and cold starts near receptors.
- Combustion plant. Biomass boilers, CHP units and standby generators need their stack emissions considered.
- Demolition and earthworks. Dust from construction is screened separately under the IAQM construction dust guidance (v2.2, January 2024); demolition near homes almost always warrants a dust risk assessment.
The EPUK/IAQM guidance was updated in 2026 with a stronger emphasis on health effects and population exposure rather than compliance alone — reflecting Defra's interim PM2.5 guidance — so screening decisions increasingly consider exposure even outside formally declared AQMAs.
Screening outcomes: statement, simple assessment or full assessment
There are three broad outcomes, and they carry very different costs and timescales:
- Screened out. A brief air quality statement records why no assessment is needed. Keep it on file — it prevents a validation query later.
- Simple assessment. Existing monitoring and Defra background maps are used to describe conditions and demonstrate the impact is negligible, with proportionate mitigation such as electric vehicle charging and low-NOx heating.
- Full assessment. Detailed dispersion modelling of road traffic or plant emissions, impact descriptors for each receptor, and a mitigation package. Usually reserved for larger schemes, AQMA sites and combustion plant.
Skipping the exercise is a false economy: air quality is a material planning consideration under the NPPF, many councils list an air quality statement on their validation checklists, and a late objection from an environmental health officer can stall a determination by months.
What you need to hand before screening a site
Screening is quick when the right facts are assembled first. For any UK site, gather:
- AQMA status — whether the site is inside or adjacent to a declared Air Quality Management Area, and for which pollutant;
- Background concentrations — Defra's background maps give modelled NO₂, PM10 and PM2.5 values for every 1 km grid square;
- Local monitoring — the council's most recent Annual Status Report shows measured concentrations at diffusion tubes and analysers near your site;
- Traffic assumptions — expected trip generation, HGV movements and parking numbers from the transport statement, so the two documents tell the same story;
- Plant and heating strategy — whether the scheme is all-electric (which removes most operational combustion issues at a stroke) or includes gas plant, CHP or generators;
- Smoke control area status — relevant for any scheme proposing solid-fuel appliances.
Councils increasingly look for proportionate mitigation even on screened-out schemes: electric vehicle charging provision, low-NOx or all-electric heating, and a construction dust management plan are the common asks, and conceding them early is cheaper than a condition negotiated late.
How Fortress Associates can help
Fortress Associates provides an automated air quality assessment service covering every UK local authority. The report is free, is generated in minutes, and draws on live official datasets — Defra background concentration maps, national AQMA boundaries, monitoring network data and DfT traffic counts — following the EPUK/IAQM criteria, IAQM dust guidance (v2.2, January 2024) and Defra LAQM.TG(22). If you are unsure whether your scheme screens in, get in touch or browse our other planning report services.
Sources & further reading
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