Particulate Matter (PM) , consists of tiny particles floating freely in the air (forming part of the so-called atmospheric aerosol). They may be of natural origin – e.g. mineral dust, sea spray, volcanic ash, etc., they may also be a product of human activity. This group includes, e.g., tiny particles of carbon black resulting from the combustion process of coal or other fuels or secondary dust particles that result from the transformation of other pollutants present in air such as sulfur and nitrogen oxides.
Two basic types of dust are distinguished in air quality analyzes: