particulate matter

n. (Abbr. PM)
Material suspended in the air in the form of minute solid particles or liquid droplets, especially when considered as an atmospheric pollutant.

Variant: PM

Matter present as small particles. Particulate matter, also known as particulates, is produced as an airborne pollutant in many processes. It may be inorganic, e.g. silicate or carbon, or organic, e.g. polyaromatic hydrocarbons (PAHs). Particulates are classified by size; e.g. PM10, with particles less than 10 μm and PM2.5, with particles less than 2.5 μm.

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particulate matter

Atmospheric particles of dust, pollen, soot, salt, sulphur, etc.