“Particulate matter,” or PM, can refer to matter found in sea spray and dust but it is most often used to refer to the complex mixture of extremely small particles and liquid droplets that constituent the pollution associated with the burning of fossil fuels, such as coal, oil and peat and emissions from road traffic, in particular diesel engines. PM that is less than ten micrometres in size (PM10) and smaller, such as PM 2.5 and what is called Fine Particulates, penetrate deep into the respiratory system increasing the risk of respiratory and cardiovascular disorders. Particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles.” PM can be emitted directly from burning of fossil fuels (primary PM) and it can form by reactions of gases such as sulphur dioxide and ammonia (secondary PM).
Until about several years ago, air pollution from burning of fossil fuels was measured as “black smoke.” EU Directive 1999/30/EC (CEC, 1999) replaced black smoke as a measure of air pollution and adopted PM as the new measure. The EU established limit values for PM10 mass concentration levels. The PM10 daily mean limit of 50 ug/m3 (micrograms per cubic meter) should not be exceeded more than 35 times per calendar year. The annual mean PM10 limit value is 40 ug/m3.
When weather conditions trap air on the surface, especially in urban areas, the PM can be especially dangerous. The London Fog of December 1952, through a combined weather inversion and heavy use of coal for domestic fireplaces, trapped black smoke, or PM, for several days killing from 4,000 to 12,000 people.
Some further ideas to explore on PM:
Can you identify all the sources of PM within 300 meters of your home, school, church, or other location.
Where is the nearest location of any measuring device that samples for PM. How does it measure for PM and how frequently?
How can we control the levels of PM in the air we breathe, especially PM emissions from road traffic?
See resources cited in footnotes above, and:
European Community emission inventory report 1990-2007 under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP), Technical report No 8/2009
Particulate matter – air quality www.epa.ie/environment/air/quality/pm/