Health Effects of Smoke

Occasionally throughout the year, smoke from forest fires, large city fires and/or stubble burning can impact the quality of life here in the city or in areas closer to the source of the fire. The effect on the health of the population depends on a number of factors.

Risk to Residents

Most healthy adults and children will recover quickly from smoke exposures and will not suffer long-term consequences. However, certain sensitive populations may experience more severe short-term and chronic symptoms from smoke exposure. These populations include:

  • Individuals with asthma and other respiratory diseases
  • Individuals with cardiovascular disease (e.g. heart disease, angina)
  • Older Adults
  • Children
  • Pregnant women
  • Smokers

The effects of smoke range from eye and respiratory tract irritation (e.g. sore eyes, tears, cough, runny nose) to more serious disorders including the worsening of underlying conditions such as asthma, chronic obstructive pulmonary disease (COPD) and heart disease, which can result in premature death.

General recommendations for the public

  • If you develop symptoms, in particular those suggestive of lung or heart problems, consult a health-care provider or call Health Links-Info Santé at 788-8200 as soon as possible.
  • Be alert to media and public service announcements for current air quality conditions, forecasts and recommendations from public health.
  • Check the current Air Quality Health Index (AQHI) for Winnipeg (see below for additional information about the AQHI).
  • Consideration should be given to canceling outdoor events such as athletic games or competitions if air quality deteriorates significantly

Additional recommendations for people with chronic diseases

  • Have an adequate supply of medication (more than 5 days) and develop a plan together with your health care provider for how to manage your condition during periods of poor air quality. 

Specific strategies

1. Staying Indoors

The effectiveness of staying indoors during a poor outdoor air quality event depends on the quality of the indoor air environment. Staying indoors can usually provide some protection, especially in a tightly closed house in which the heating/cooling system can be set to re-circulate air instead of bringing in outdoor air. In homes without re-circulating systems, indoor concentrations of fine particles can approach 70 to 100 percent of the outdoor concentrations.

2. Reducing activity level

Reducing physical activity is an important and effective strategy to lower the dose of inhaled air pollutants and minimize health risks during a smoke event. During exercise, people can increase their air intake as much as 10 to 20 times above their resting level.

3. Reducing other sources of indoor air pollution

Many indoor sources of air pollution can emit large amounts of the same pollutants present in smoke from fires. Indoor sources such as burning cigarettes, gas, propane and woodburning stoves and furnaces, and activities such as cooking, burning candles and incense, and vacuuming can greatly increase the particle levels in a home and should be avoided during high pollution or when wildfire smoke is present. Devices such as ozone generators should not be used.

4. Masks

  • In general, wearing a mask is not an effective exposure reduction strategy during a smoke event.
  • In order for a mask to provide protection, it must be able to filter very small particles and it must fit well, providing an airtight seal around the wearer's mouth and nose.
  • Commonly available paper dust masks, which are designed to filter out larger particles, such as sawdust created by sanding, typically offer little protection. In fact, masks may actually be detrimental, giving the wearers a false sense of security, which may encourage increased physical activity and time spent outdoors, resulting in increased exposures. They can also make breathing more difficult.
  • Respirator forms of masks are able to filter most particulate matter. These masks, which may include an exhalation valve, do not require cartridge filters. They are marked with one of the following: "R95", "N95" or "P95", and are typically sold at home improvement stores. Soft masks with higher ratings (R, N or P99, and R, N, or P100) are also available and will filter out even more particles.
  • Respirators with purple HEPA filters offer the highest protection, but may be less comfortable and slightly more expensive than the flexible masks.
  • Individuals who wish additional protection may purchase tight-fitting respirators that require cartridge filters.

Air Quality Health Index (AQHI)

The Air Quality Health Index (AQHI), developed by the Government of Canada and adopted by the Manitoba government, helps people understand how poor air quality can affect their health and provides steps they can take. The AQHI is an indicator of air quality, based on hourly measurements of three important air pollutants: ground-level ozone (O3), nitrogen dioxide (NO2) and fine particulate matter (PM2.5). Manitoba Conservation calculates the AQHI for Winnipeg from readings made from monitors in downtown Winnipeg. The AQHI uses a colour-coded scale, from 1 to 10+. The higher the number, the greater the health risk associated with air quality. The numbers are also grouped into risk categories - low, moderate, high and very high - that help the user to quickly identify their level of risk.

AQHI Categories and Messages

Health Risk 
Health Messages
At Risk Population* General Population
Low 1 - 3 Enjoy your usual outdoor activities. Ideal air quality for outdoor activities.
Moderate 4 - 6 Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms. No need to modify your usual outdoor activities unless you experience symptoms such as coughing and throat irritation.
High 7 - 10 Reduce or reschedule strenuous activities outdoors. Children and the elderly should also take it easy. Consider reducing or rescheduling strenuous activities outdoors if you experience symptoms such as coughing and throat irritation.
Very High Above
Avoid strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion. Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation.

* People with heart or breathing problems are at greater risk. Follow your doctor's usual advice about exercising and managing your condition.


Other Facts about Smoke and Air Quality

  • Smoke is composed primarily of carbon dioxide, water vapor, carbon monoxide, particulate matter, hydrocarbons and other organic chemicals, nitrogen oxides, trace minerals and several thousand other compounds.
  • Particulate matter is the principal pollutant of concern from smoke and is a generic term for particles suspended in the air, typically as a mixture of both solid particles and liquid droplets, which can be inhaled into the lung.
  • Carbon monoxide is another pollutant of concern. Carbon monoxide is a colorless, odorless gas, produced by incomplete combustion of wood or other organic materials. Levels are highest during the smoldering stages of a fire.
  • Other air pollutants, such as acrolein, benzene, and formaldehyde, are present in smoke, but in much lower concentrations than particulate matter and carbon monoxide.

The behavior of smoke depends on many factors, including the fire's size and location, the topography of the area and the weather. Smoke levels are unpredictable and can change frequently.

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