UK air pollution improved between 2015 and 2024, but is still dangerous too often, research from the University of Reading says in ‘Environmental Science: Atmospheres’. Scientists from the University studied pollution at more than 500 monitoring sites around the UK. They found that two types of pollution got better over the decade: nitrogen dioxide (NO2), which is mainly produced by traffic, fell by 35% on average at monitoring sites; and fine particles called PM2.5, which are small enough to get deep into lungs, dropped by 30%.

Nevertheless, pollution still breaks safety limits too often. The average number of days each year when NO2 exceeded World Health Organisation targets fell from 136 to 40 days, while for PM2.5 particles exceedances decreased from 60 to 22 days per year.

In contrast to NO2 and PM2.5, another pollutant, surface ozone (O3), increased by 17% on average over the decade. The number of days when O3 exceeded targets doubled from 7 to 14 per year.

These findings mean different approaches are needed to tackle each type of pollution, pointed out the authors, James Weber and Helen Dacrea. NO2 pollution is mainly driven by local traffic, while PM2.5 particles often come from other parts of the UK and continental Europe. Ozone pollution comes from both local and distant sources.