Traffic is one of the biggest sources of poor air quality, so when a development adds vehicle movements, air quality is one of the things a planning authority will want answered. The link runs straight from transport to emissions, which is why the two are best dealt with together. Here is when air quality comes into a planning application, what an assessment covers, and how a scheme shows it has done enough.
Why air quality is a planning issue
Road traffic puts nitrogen dioxide and fine particles into the air, and both carry a real health cost, particularly near busy roads and junctions. Where levels breach national objectives, a council declares an Air Quality Management Area and has to work to bring them down. National policy through the NPPF asks development not to make air quality worse and to take opportunities to improve it. So a scheme that generates traffic, or puts people in a place that already has a problem, has to show it has thought the issue through rather than added to it.
When a development has to look at it
Not every scheme needs a full assessment, but several triggers put air quality on the table. A site inside or near an Air Quality Management Area. A development that generates enough new traffic to change pollutant levels on surrounding roads. A sensitive use, homes, a school or a care setting, proposed close to a busy road where future occupiers would be exposed. And the construction phase itself, where dust and site traffic need managing. Working out early which of these apply decides the level of assessment a scheme needs and keeps it proportionate.
What an air quality assessment covers
An assessment generally looks at two phases. Construction, where the focus is dust and the traffic and plant on site, managed through a method statement and sensible controls. And operation, where the focus is the traffic the finished development generates and the pollutant levels at nearby receptors, the homes, schools and public spaces where people spend time. The operational work draws directly on the transport evidence, because the traffic figures that feed a transport assessment are the same figures that drive the emissions, which is why the two pieces of work belong together.
The link between traffic and air quality
The cleanest way to protect air quality is to generate fewer and cleaner vehicle trips in the first place. A scheme that is designed for walking, wheeling and cycling, sits near public transport, and makes electric vehicle charging easy will put less into the air than one that leaves the car as the only option. That is the same provision that strengthens the transport case, so good transport planning and good air quality outcomes tend to move together rather than pull apart. Reducing the trips is worth more than treating the emissions after the fact.
Mitigation that carries weight
Where a scheme does have an effect, the mitigation has to be real and secured, not just described. The measures that count are the ones built into the design: active travel routes and cycle parking, electric vehicle charging, a travel plan that reduces car trips, and layout that keeps sensitive rooms and gardens back from the worst of the roadside air. Where an effect remains after all that, some authorities look for a contribution calculated on the damage-cost approach, put towards local air quality measures. Mitigation that is designed in and committed to through the application is far stronger than a promise to deal with it later.
How we help
We assess the air quality effects of a scheme alongside its transport, using the same traffic evidence for both, and build the mitigation into the design and the application so it holds up. It sits within our transport planning and planning application work, so transport and air quality are answered together rather than in separate silos. If you have a site near a busy road or an Air Quality Management Area, get in touch.
