Microscopic solid or liquid matter suspended in the Earth's atmosphere / From Wikipedia, the free encyclopedia

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Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM) or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The term aerosol commonly refers to the particulate/air mixture, as opposed to the particulate matter alone.[1] Sources of particulate matter can be natural or anthropogenic.[2] They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.

Types of atmospheric particles include suspended particulate matter; thoracic and respirable particles;[3] inhalable coarse particles, designated PM10, which are coarse particles with a diameter of 10 micrometers (μm) or less; fine particles, designated PM2.5, with a diameter of 2.5 μm or less;[4] ultrafine particles, with a diameter of 100 nm or less; and soot.

The IARC and WHO designate airborne particulates as a Group 1 carcinogen.[5] Particulates are the most harmful form (other than ultra-fines) of air pollution[6] due to their ability to penetrate deep into the lungs and brain from the blood streams, causing health problems including cardiovascular disease, respiratory disease, and premature death.[7] In 2013, a study involving 312,944 people in nine European countries revealed that there was no safe level of particulates and that for every increase of 10 μg/m3 in PM10, the lung cancer rate rose 22% (95% CI [1.03–1.45]). The smaller PM2.5, which can penetrate deeper into the lungs, were associated with an 18% increase in lung cancer per 5 μg/m3; however, this study did not show statistical significance for this association (95% CI [0.96–1.46])[8] Worldwide exposure to PM2.5 contributed to 4.1 million deaths from heart disease and stroke, lung cancer, chronic lung disease, and respiratory infections in 2016.[9] Overall, ambient particulate matter ranks as the sixth leading risk factor for premature death globally.[10]