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 PM_2.5 or respirable particles because it penetrates the respiratory system further than larger particles.

PM_2.5 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?

PM_2.5 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 PM_2.5 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 per cent of Ontario's PM_2.5 comes from the U.S.

PM2.5 Composition/Emissions
Pie Chart	Category	Percent
	Elemental and Organic Carbon1 (Combustion Related)	30% - 50%
	Sulphate4	30% - 40%
	Nitrate2	10% - 20%
	Soil3	3% - 10%

Notes:

1. Transportation, wood burning, utility/commercial fuel combustion, plus secondary organic aerosols formed from precursor VOC emissions.
2. Formed from NO_x emitted from regional and local sources: transportation, utilities, and industries.
3. Fugitive dust (paved roads, construction), and industries.
4. Formed from SO₂ and SO₄ emitted from regional and local sources: oil and coal-fired utility and commercial/industrial boilers, small combustion sources, transportation, smelters.

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 PM_2.5 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.

The following table shows the health effects of different AQI levels caused by fine particulate matter.

Health effects of different Air Quality Index (AQI) levels caused by fine particulate matter
Category	AQI	Fine Particulate Matter (PM2.5)
Very Good	0 - 15	Sensitive populations may want to exercise caution.
Good	16 - 31	Sensitive populations may want to exercise caution.
Moderate	32 - 49	People with respiratory disease at some risk.
Poor	50 - 99	People with respiratory disease should limit prolonged exertion; general population at some risk.
Very Poor	100 or over	Serious respiratory effects even during light physical activity; people with heart disease, the elderly and children at high risk; increased risk for general population.

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