school energy&environment

Atmospheric dust

Atmospheric dust consists of a mixture of solid and liquid particles suspened in the atmosphere varying in composition, source and size. Atmospheric dust particles can be removed out of the atmosphere by dry and wet deposition and fall back on soil, vegetation or watercourses. Atmospheric dust particles can be classified according to their diameter (measured in micrometers or µm. 1000 micrometers equivalent to 1 millimeter) ranging from 0,005 to 100 µm. Within this interval atmospheric particles are classified as:

• primary particles – diameter ranging from 2,5 to 30 µm;
• secondary particles – diameter lower than 2,5 µm.

Primary particles form from combustion, soil erosion and disintegration. Pollen and spores figure in this category. Secondary particles are generated by vehicular traffic, industrial activities and thermoelectrical implants. Atmospheric dust particles with a diameter of less than 10 µm and 2,5 µm draw special attention and are defined PM₁₀ and PM_2,5 (PM= Particular Matter), respectively. PM_2,5 particles are a subset of PM₁₀ and count for 60% of its weight. PM₁₀ is an inhalable particle as it can travel deep into the breathing apparatus to the larynx; and it’s also breathable as it can settle in the pulmonary alveoli. These dust particles raise serious health concerns as they have been linked to a number of breathing and cardiovascular diseases. Sources of dust particles can be natural (volcanic eruption, sea aerosols, spores, pollen, soil erosion,…) or man-made (vehicular traffic, industrial emissions and combustion processes).