Notable events
| Start year | End year | Sector | Information | Impact |
| 2020 | 2020 | Road transport, aviation and railways | Because of measures in place during the COVID-19 pandemic, PM2.5 emissions from road transport, aviation and railways in 2020 were 23%, 61% and 28% 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 8.3% 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 66% 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 99.9% since 1990. Residential sector emissions fell between 1990 (47kt) to 2002 (20kt), reflecting declining coal use. Industrial use of biomass fuels is increasing and has, as a result, become a more significant contributor to UK emissions – 18% of UK emissions of PM2.5 in 2021.
Emissions of PM2.5 will need to be reduced by 25% based on the 2021 total to meet the 2030 National Emissions Ceilings Regulations and Gothenburg Protocol targets.