Atmospheric aerosol particles, also known as atmospheric particulate matter, particulate matter (PM), particulates, or suspended particulate matter (SPM) are microscopic solid or liquid matter suspended in Earth’s atmosphere. The term aerosol commonly refers to the particulate/air mixture, as opposed to the particulate matter alone. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health.
Subtypes of atmospheric particles include suspended particulate matter (SPM), thoracic and respirable particles, inhalable coarse particles, which are [coarse] particles with a diameter between 2.5 and 10 micrometers (μm) (PM10), fine particles with a diameter of 2.5 μm or less (PM2.5), ultrafine particles, and soot.