Particles in the air arise from a wide variety of sources, either man-made or natural. A range of particle sizes occur in the atmosphere, some causing a general nuisance in terms of their ability to spoil furniture, clothing etc. and others of such a small dimension that they can enter the upper respiratory tract. Particles with a general diameter of 10 microns or less (PM10) have been found to have a significant health risk.
Sources
Man-made particles result from combustion processes, mineral workings, industrial processes and from the attrition of road surfaces by motor vehicles. Natural sources – wind raised dust from open fields, sea spray, emissions from animals and plants (microbial and fungal spores), volcanoes, and forest fires. The atmospheric lifetime of particles is related to it’s size. Larger particles (10 microns in diameter) may be airborne for up to 20 hours and may travel 20 to 30 km, while smaller particles may travel several thousand km.
Health effects
Particulate pollution is associated with a range of effects on health including effects on the respiratory and cardiovascular systems, asthma and mortality. EPAQS concluded that particulate pollution episodes are responsible for causing excess deaths among those with pre-existing lung and heart disease. They also concluded that there is a relationship between concentrations of PM10 and health effects, such that the higher the concentration of particulates, the greater the effects on health.
