Briefing: Ultra-fine particles from aviation

15th April, 2026

Particulate Matter (PM) describes solid and liquid particles in the air that are typically classified by their size, for example PM2.5 and PM10 (particles smaller than 2.5 and 10 micrometers respectively).

Ultrafine particles (UFPs) are the smallest category of PM, having a diameter less than 0.1 micrometers. UFPs tend to make up a small fraction of particle mass but a large proportion of the number of particles in the air. UFPs are emitted from all combustion processes, such as burning coal in industry or fuels for transport. Road vehicles are the major urban source, although UFPs from aircraft can disperse tens of kilometres from airports. Sulphur in fuels contributes to the presence of UFPs, with kerosene having a much higher sulphur content than road fuels. It is thought that UFPs from aviation have different compositions than road-sourced UFPs.

AEF has put together a full briefing detailing the current policies and policy blockers for UFP regulation and recommendations for future policies to combat this air pollution.

Photo credit: Amir Mortezaie, UnSplash