懸浮顆粒（particulate matter，PM）又稱细颗粒物、颗粒物、粒状物，简称颗粒（particulates）或微粒，泛指悬浮在空气中的固体颗粒或液滴，顆粒微小 ...

A report that assessed the health effects of improved air quality in China highlighted a sharp reduction in PM2.5 — particulate matter with a diameter of 2.5 micrometers or less — exposure.