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Air Pollution Particulate Matter

3. How are we exposed to Particulate Matter?

  • 3.1 Critical sources of PM or its components responsible for health effects
  • 3.2 Relationship between ambient levels and personal exposure to PM
  • 3.3 Short-term exposure to high peak levels and exposure in hot spots for PM

3.1 Critical sources of PM or its components responsible for health effects

WHO states: "Short-term epidemiological studies suggest that a number of source types are associated with health effects, especially motor vehicle emissions, and also coal combustion. These sources produce primary as well as secondary particles, both of which have been associated with adverse health effects. One European cohort study focused on traffic-related air pollution specifically, and suggested the importance of this source of PM. Toxicological studies have shown that particles originating from internal combustion engines, coal burning, residual oil combustion and wood burning have strong inflammatory potential. In comparison, wind-blown dust of crustal origin [that is, from the Earth’s crust] seems a less critical source." More...

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3.2 Relationship between ambient levels and personal exposure to PM

Can the differences influence the results of studies?

Personal exposure to PM and its components varies from person to person and is influenced by outdoor sources as well as by indoor sources, such as tobacco smoke.

On a population level and considering variations over time, there is a clear relationship between the ambient level of PM and the level of personal exposure to PM, especially for fine combustion particles. Thus, measurements of PM in ambient air can serve as a reasonable approximation of personal exposure in time-series studies.

Fewer studies have addressed whether ambient long-term PM concentrations are a good indicator of average/long-term PM exposure. Contributions to personal PM exposure from smoking and professional activities need to be taken into account. More...

3.3 Short-term exposure to high peak levels and exposure in hot spots for PM

Adverse health effects have been documented after short-term exposure to peak levels of particulate matter (PM), as well as after long-term exposure to moderate concentrations. However, the impact of long-term exposure on public health is probably larger than that of short-term exposure to peak concentrations. Long-term exposure to moderate levels of fine PM has been estimated to reduce life expectancy by as much as several months. Nevertheless, numerous deaths and serious cardiovascular and respiratory problems have been attributed to short-term exposure to peak levels.

Areas near busy roads where concentrations of PM components, such as elemental carbon and ultrafine particles, are particularly elevated are referred to as “hot spots”.
In urban areas, up to 10% of the population may be living in these hot spots. The public health burden of such exposures is therefore significant. Unequal distribution of health risks between groups of people also raises concerns of environmental justice and equity. More...


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