Average annual particulate matter concentrations at roadsides in the UK 2000-2023
The average concentration of PM2.5 measured at UK roadside sites was 7.7 micrograms per cubic meter air (µg/m3) in 2023. Roadside PM2.5 levels in central London have decreased by roughly 40 percent since 2017, owing to various policies like Ultra Low Emissions Zones and zero-emission vehicles. PM2.5 are defined as particulate matter of 2.5 micrometers or less in diameter and are responsible for thousands of premature deaths every year in the UK.