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| Last Updated:: 01/04/2016

Fine Particulate Matter

What is fine particulate matter?

Particulate matter is characterized according to size - mainly because of the different health effects associated with particles of different diameters. Particulate matter is the general term used for a mixture of solid particles and liquid droplets in the air. It includes aerosols, smoke, fumes, dust, ash and pollen. The composition of particulate matter varies with place, season and weather conditions. Fine particulate matter is particulate matter that is 2.5 microns in diameter and less. It is also known as PM2.5 or respirable particles because it penetrates the respiratory system further than larger particles. PM2.5 in Ontario is largely made up of sulphate and nitrate particles, elemental and organic carbon and soil.


What are the sources of fine particulate matter?

PM2.5 material is primarily formed from chemical reactions in the atmosphere and through fuel combustion (e.g., motor vehicles, power generation, industrial facilities, residential fire places, wood stoves and agricultural burning). Significant amounts of PM2.5 are carried into Ontario from the U.S. During periods of widespread elevated levels of fine particulate matter, it is estimated that more than 50% of Ontario's PM2.5 comes from the U.S.


What are the effects of fine particulate matter?

The greatest effect on health is from particles 2.5 microns or less in diameter. Exposure to fine particulate matter has been associated with hospital admissions and several serious health effects, including premature death. People with asthma, cardiovascular or lung disease, as well as children and elderly people, are considered to be the most sensitive to the effects of fine particulate matter. Adverse health effects have been associated with exposure to PM2.5 over both short periods (such as a day) and longer periods (a year or more).

Fine particulate matter is also responsible for environmental effects such as corrosion, soiling, damage to vegetation and reduced visibility.