Where there is smoke ... there is air pollution

On Monday, smoke wafting from more than 50 forest fires in Northern Quebec made headlines across the country as cities as far away as Montreal, Ottawa and Detroit were caught in the haze. 

A small amount of rain reduced the number of fires to 41 on Tuesday, with six classified as out of control, the Montreal Gazette reports.  

Adults breathe an average of 15,000 to 20,000 litres of air every day. Most air, indoor and outdoor, contains some pollutants.

Pollution is usually linked to man-made sources, such as industrial pollution and vehicle emissions, but humans aren't the only source of air pollution.

Forest fires also create intense air pollution. Biomass combustions — the burning plant life — give off carbon monoxide, carbon dioxide, methane and particulate matter. Depending on the type of plants being burned, smoke can also contain nitrogen, sulfur and other harmful chemicals.

The effects of smoke from forest fires:

Smoke from forest fires contains many airborne particles, known as particulate matter (PM). Particulate matter is generally divided into two categories: course and fine. Fine particulate matter is smaller than 2.5 micrometres (PM2.5) and is dangerous to inhale because the particles are small enough to travel to the very bottom the lungs.

While most of the Health Canada and Environment Canada guidelines for PM2.5 emissions are focused on industry pollution, an average of one third of all PM2.5 emissions in Canada come from forest fires every year.

How to protect yourself:

In order to prevent yourself from being exposed to harmful amounts or air pollutants, the first step is to be informed.

Check the Air Quality Health Index (AQHI) for your area. The AQHI is an initiative by Environment Canada that rates air quality in major Canadian cities on a 10-point scale. A rating between one and three is considered zero to low risk, while a rating of eight to 10 is considered very high risk. For example on Monday, the AQHI index for both Montreal and Ottawa was eight and came with a health advisory calling on people to avoid all outdoor activity. By Tuesday, the AQHI measured as three to four with a health advisory suggesting people reduce outdoor activity.

If there is an air quality warning in your area, or you notice yourself being irritated by outdoor air, avoid any strenuous outdoor activity. Exercising in polluted air worsens the effect. The same can be said for exercising in a regularly polluted area, such as running next to a busy roadway during rush hour.

The smog effect

Smog is composed mainly of ground-level ozone. Ozone is three oxygen molecules bound together and at the ground level, is usually created by sunlight reacting with volatile organic matter, nitrous oxides and regular oxygen compounds.

Particulate matter is closely tied with smog because it provides the necessary ingredients for the chemical reaction that makes ozone.  

The health effects from inhaling smog are the same as the effects of breathing smoke, though the thick, chemical haze that often hangs over Canadian cities is more dangerous because of the harmful contaminants it contains.