Particulate matter
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:
PM10, i.e. particulates with particle diameters less than 10 μm. It is so small that it penetrates deep into the respiratory system. A portion of this particulate, with particle diameters in the range of 2.5 to 10 μm, is termed as "coarse dust particles". The composition of this fraction consists of primarily mineral particles, carried from the ground by the wind or on construction sites, carried by car traffic, etc. Due to the relatively large particle size, the thick dust reaches the respiratory system no deeper than to the bronchi.
PM2.5 i.e. fine particles with particle diameters below 2.5 μm. On average, it accounts for about 60% of PM10 in summer and over 75% in winter seasons. It consists primarily of soot and other products created during the combustion process. It poses a high risk to human health , because of the small particle size it can penetrate the deepest parts of the respiratory system, into the pulmonary alveoli and into the bloodstream.
