Notable events
| Start year | End year | Sector | Information | Impact |
| 2020 | 2020 | Road transport and aviation | Because of measures in place during the COVID-19 pandemic, PM2.5 emissions from road transport and aviation in 2020 were 22% and 60% lower than they had been in 2019 respectively. | Decrease in emissions |
| 2021 | 2021 | Road transport | As a result of easing COVID-19 restrictions, PM2.5 emissions from road transport in 2021 were 8.1% higher than they had been in 2020 | Decrease in emissions |
Particulate matter with an aerodynamic diameter of less than 2.5 micrometres (µm) is referred to as PM2.5.
In general, emissions of finer particulates follow similar trends as for PM10. UK emissions of PM2.5 have declined by 75% since 1990 due mainly to a reduction in coal use, and the banning of crop residue burning in 1993. Emissions from coal-fired power stations have fallen by 100% since 1990. Residential sector emissions fell between 1990 (40kt) to 2005 (13kt), reflecting declining coal use. As other sources of emissions have declined, those from domestic combustion have become an increasingly important share of emissions, increasing from 15% in 1990 to 17% in 2023. Industrial use of biomass fuels is increasing and has, as a result, become a more significant contributor to UK emissions – 6% of UK emissions of PM2.5 in 2023.
Emissions of PM2.5 will need to be reduced by 14% based on the 2023 total to meet the 2030 National Emissions Ceilings Regulations and Gothenburg Protocol targets.