There are two forms of air pollution we are concerned about and which we measure. The first is particulate matter (PM), referred to as PM10 and PM2.5, depending on the size of particles being measured. The second is nitrogen dioxide (NO2). Concentrations of both vary across the city and according to the season, the weather and the time of day (mostly due to changing traffic volumes).

PM and NO2 is monitored in Bristol at various locations across the city. The PM levels at our monitoring sites have been below the EU and UK limits for several years. However, the levels of NO2 currently exceed EU and UK limits.

The results from our monitoring work consistently show much higher levels of NO2 near busy roadsides, and lower levels away from roadsides and traffic, indicating a direct link between vehicle movements and air quality.

Like NO2 pollution, we know PM pollution is linked to poor health. By tackling NO2 pollution, we will also help lower PM levels.