2. Definition
Mass and composition in PM tend to be divided into three principal groups:
2.1 coarse particles
2.2 fine particles
2.3 Ultrafine particle
PM0.1 is particulate matter with an aerodynamic diameter of up to 0.1 µm, referred to as the ultrafine particle fraction.
PM2.5 is particulate matter with an aerodynamic diameter of up to 2.5 µm, referred to as the fine particle fraction
PM10 is particulate matter with an aerodynamic diameter of up to 10 µm, i.e. the fine and coarse particle fractions combined.
Coarse particles (PM10) have an aerodynamic diameter between 2.5 m m and 10 mm.
They are formed by mechanical disruption (e.g. crushing, grinding, abrasion of surfaces); evaporation of sprays, and suspension of dust.
PM10 is composed of aluminosilicate and other oxides of crustal elements, and major sources including fugitive dust from roads, industry, agriculture, construction and demolition, and fly ash from fossil fuel combustion.
The lifetime of PM10 is from minutes to hours, and its travel distance varies from <1 km to 10 km.
Fine particles have an aerodynamic diameter less than 2.5 mm (PM 2.5).
These particles are formed from gas and condensation of high-temperature vapors during combustion, and they are composed of various combinations of sulfate compounds, nitrate compounds, carbon compounds, ammonium, hydrogen ion, organic compounds, metals (Pb, Cd, V, Ni, Cu, Zn, Mn, and Fe), and particle bound water.
The major sources of PM 2.5 are fossil fuel combustion, vegetation burning, and the smelting and processing of metals.
Their lifetime is from days to weeks and travel distance ranges from 100s to >1000s km. In addition, fine particles are associated with decreased visibility ( haze) impairment in many cities of the U.S
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