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Environmental and Workplace Health

Particulate Matter

Particulate matter is the name for a wide range of airborne particles that are small enough for people to breathe in. Exposure to particulate matter found in indoor air can cause respiratory symptoms such as coughing and wheezing.

What is Particulate Matter?

Particulate matter (PM) is the name for a wide range of particles that are small enough to be carried by the air and therefore be breathed in by people. They can be solid or liquid, or a mixture of both.

The size of particles may range from 0.005 µm to 100 µm in diameter. In comparison, the average size of a human hair is 60 µm. PM10 are particles that are 10 µm or less in diameter. PM2.5 are particles of 2.5 µm or less in diameter. The finer particles pose the greatest threat to human health because they can travel deepest into the lungs.

Particulate Matter

Size of fine particulate matter. Credit to: EPA, Queensland, Australia, 2007
Credit to: Environmental Protection Agency, Queensland, Australia, 2007

Indoor particulate matter is a mixture of substances like these:

  • Carbon (soot) emitted by combustion sources;
  • Tiny liquid or solid particles in aerosols;
  • Fungal spores;
  • Pollen; and
  • A toxin present in bacteria (endotoxin).

In a properly maintained home, most of the airborne particulate matter comes from the outside. However, some homes do have significant sources of indoor particulate matter which come from the following sources:

  • Cigarette smoking is the greatest single source of particulate matter in homes and buildings where people smoke;
  • Cooking: especially frying and sautÚing;
  • Malfunctioning combustion appliances: for example, furnaces without a proper air filter;
  • Non-vented combustion appliances like gas stoves;
  • Wood-burning appliances like wood stoves and fireplaces: especially if the smoke leaks or backdrafts into the home; and
  • Mould growth.

What Are the Health Risks?

There are very few studies on the health effects of indoor particulate matter, but those available seem to link PM to respiratory symptoms such as wheezing and coughing, especially in children. Some laboratory studies also indicate that PM collected indoors can be toxic.

On the other hand, there are many studies on the effects of outdoor particulate matter on health. These studies show a wide range of respiratory and cardiovascular effects, especially in those who already suffer from a respiratory or cardiac condition.

How Can You Reduce Concentrations of Particulate Matter in Your Home?

  • Furnaces and ventilation systems: Make sure that furnaces and ventilation systems are properly maintained, and that you replace filter screens as often as recommended by the manufacturer. All combustion appliances, including furnaces, should be inspected by a qualified technician yearly.
  • Cooking: Turn your exhaust fan on when you are cooking, and especially when frying.
  • Woodstoves: Choose properly sized woodstoves and make sure that the doors close tightly. Have your chimney cleaned yearly, too.
  • Mould: Prevent mould growth and the release of mould spores into your indoor air by controlling humidity and fixing water leaks and water-damaged areas (More information on mould).
  • Smoking: Don't allow people to smoke indoors because particulate matter levels increase with every smoker in the building.
  • Clean: Use your vacuum cleaner regularly.

Where Can I Get More Information?

Did you know?

Particulate matter can be solid, liquid - or a mixture of both.