Particulate matter and aerosols
Particulate matter or particle pollution is made up of a mixture of microscopic solids and liquid droplets suspended in air. Almost all human activities produce particulate matter. The smaller the particle, the deeper it enters the body. Ultrafine particles (PM1 and smaller), such as aerosols, end up in the lungs and are especially harmful to people with lung diseases. Even low concentrations of particulate matter are harmful.