Atmospheric particulate matter – also known as particulates or particulate matter (PM) – are tiny pieces of solid or liquid matter associated with the Earth's atmosphere. They are suspended in the atmosphere as atmospheric aerosol, a term which refers to the particulate/air mixture, as opposed to the particulate matter alone.
Sources of particulate matter can be manmade or natural. They can adversely affect human health and also have impacts on climate and precipitation.
Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes also generate significant amounts of particulates.
Subtypes of atmospheric particle matter include:
Suspended particulate matter (SPM),
Respirable suspended particle (RSP; particles with diameter of 10micrometres or less),
Fine particles (diameter of 2.5 micrometres or less),
Ultrafine particles, and soot.
These cause various disorders in man including those related to the respiratory system, cancer, allergy, cardiovascular problems, eye problems etc. They also clog pores of stomata in plants, adversely affecting the vegetation.