Understanding Air Quality Data in Your Report

Air quality figures in a community report are modelled estimates for a location, not readings from a monitor physically installed at that address. Understanding how the figures are produced helps in interpreting them correctly.

Modelled data, not live monitoring

The UK does not have a physical air quality monitor on every street. Instead, national modelling combines monitoring station readings, traffic data, industrial emissions, and atmospheric dispersion modelling to estimate pollutant concentrations across the whole country at a fine geographic resolution. This is a well-established, scientifically robust approach, but it means the figure for a specific address is a statistical estimate for that immediate area, not a direct measurement taken there.

What is measured

The most commonly reported pollutants are nitrogen dioxide (NO2), largely associated with vehicle traffic, and particulate matter (PM2.5 and PM10), fine particles from a mix of traffic, industry, and domestic sources such as wood burning. Each is reported against recognised concentration bands, which allow a location to be compared against national guidelines and against other areas.

Why nearby areas can differ

Air quality can vary meaningfully over short distances, particularly near busy roads, junctions, or industrial sites. Two addresses a short walk apart can show different figures if one sits closer to a significant traffic source. This is expected and reflects genuine local variation rather than an error in the data.

How current is the figure

Modelled air quality data is typically produced annually by the relevant national environment agency, using the most recent full year of underlying monitoring and traffic data available at the time of modelling. There is inevitably some lag between real-world conditions and the published model, usually a year or so, similar to most other national environmental datasets.

Questions worth asking

• Which pollutants does the figure cover, and against what guideline is it being compared?
• Is the address close to a major road, junction, or industrial site that could explain a locally elevated reading?
• How does the figure compare to the wider city or region, not just a single neighbouring postcode?