Date: June 25, 2019

A few showers ending after midnight then mainly cloudy. Risk of a thunderstorm late this evening and after midnight. Wind becoming southwest 20 km/h after midnight. Low 17.


Environment Canada
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Indoor Air Quality

This page was reviewed or revised on Friday, June 10, 2016 8:57 AM

Since we spend up to 90% of our time indoors, the quality of the air in our homes and workplaces is an important health concern. Indoor air quality (IAQ) can be a problem in both new and old homes and buildings. New carpets, fabrics and building materials can be sources of indoor air contaminants, while older homes often have a build up of dust, mould and moisture problems. Tobacco smoke, wood stoves, cleaning products and even the family pet can be sources of poor IAQ.

IAQ can affect us all, but those with asthma or other respiratory illnesses are particularly susceptible. Symptoms that are commonly attributed to IAQ include:

  • Headaches, fatigue, and shortness of breath
  • Sinus congestion, cough, and sneezing
  • Eye, nose, throat and skin irritation
  • Dizziness and nausea

This section provides information about common indoor air pollutants and provides solutions for you to improve indoor air quality in your home. 

Links to indoor air quality information:

Health Canada - Indoor Air Quality

The Lung Association - Your Healthy Home

Indoor Air Pollutants

Indoor air pollutants that affect human health can be classified as either biological or chemical. Biological pollutants are living things or are by-products of living things (e.g. mould, animal dander). Chemical pollutants are gases or particles that come from a variety of sources (e.g. household products, paints, oil or gas appliances).

Other Biological Contaminants

Other biological pollutants include bacteria, viruses, animal dander and saliva, house dust mites, cockroaches, and pollen. These pollutants come from humans, pets and insects, and can grow on various surfaces and stagnant water. Some biological agents may cause infectious diseases or allergic reactions.

Biological agents can be reduced by keeping surfaces dust-free, reducing relative humidity, and maintaining a high standard of personal hygiene.

Chemical Pollutants

Environmental Tobacco Smoke (ETS)

Environmental tobacco smoke (ETS) is the mixture of smoke that comes from the burning end of a cigarette, pipe, or cigar, combined with smoke exhaled by the smoker. It is a complex mixture of over 4,000 compounds and at least 50 are known to cause cancer in humans or animals. ETS is often referred to as “secondhand smoke.” ETS causes eye, nose and throat irritation, headache, nausea, dizziness, appetite loss, and aggravation of asthma and angina pectoris. 

Products of Combustion

Carbon monoxide is a colourless, odourless, poisonous gas. It is produced by the incomplete combustion of organic compounds such as firewood and tobacco. Major sources of carbon monoxide in the home include faulty furnaces and unvented kerosene space heaters.

Carbon monoxide decreases exercise capacity, impairs psychomotor performance, and is fatal at high concentrations. If you think your furnace is faulty, call your local utility company.

You can reduce carbon monoxide levels in your home by making sure your furnace has an adequate air supply, your fireplace is drawing air well, and your kerosene lamps and heaters are well ventilated. Do not use kerosene-burning appliances in tents or trailers. Carbon monoxide detectors are available at most department stores.

Nitrogen dioxide is a reddish-brown gas with a pungent and irritating odour. Outdoor sources are industrial and automobile emissions; indoor sources include gas stoves and unvented combustion appliances. Nitrogen dioxide levels tend to be higher in homes with gas stoves, ranges and water heaters. Nitrogen dioxide levels can be reduced by ensuring adequate ventilation of all fuel burning appliances.

Long-term exposure to sufficient levels of nitrogen dioxide may lead to an increased risk of developing a respiratory illness.

Carbon dioxide is a colorless, odourless, inflammable gas produced by fossil fuel combustion and human metabolism. High levels of carbon dioxide may cause fatigue, headache, increased perception of warmth and unpleasant odours.

Particulate Matter

Particulate matter consists of extremely small solid or liquid particles suspended in the air (i.e. smoke, dust). The main sources of particulate matter indoors are cooking (particularly if wood, coal or oil is used as fuel), heating and ventilation systems, cleaning, dusting, unvented dryers and tobacco smoke. The level of particulate matter is often higher indoors versus outdoors.

There are numerous health effects associated with particulate matter. The particles mainly affect the lungs and appear to aggravate pre-existing lung and heart disease. The elderly, those with chronic pulmonary or cardiovascular disease, and young children are most sensitive to high levels of particulate matter.

There are numerous ways to reduce particulate matter. For instance, make sure filters on furnaces and air conditioners are properly installed, cleaned and maintained. In addition, use deionized water or distilled water in indoor humidifiers. Finally, eliminate tobacco smoke from the home.

Household Products

Household products that contribute to indoor air pollution include volatile organic solvents, pesticides, disinfectants, hair sprays, and other products. Consumer products containing solvents include cleaning fluids, cleansers, paint, art supplies and pest control products.

Short term exposure to solvent vapours can cause temporary dizziness. Prolonged or repeated exposure irritates the eyes, lungs, and skin, and damages the nervous system, liver and kidneys, depending on the level and duration of exposure. Each product has unique health effects associated with it. When using these products, make sure that the area is well ventilated, and follow the directions printed on the labels. Proper use of these products minimizes the amount of indoor air pollution created.


Formaldehyde is a colourless gas with a pungent odour. Formaldehyde can be found in the home in particle board, new fabric, aerosol cans and insulation.

In the 1970s through 1982, urea formaldehyde was used in homes as insulation. Basically, holes were drilled in the exterior wall of the homes and the mixture was pumped into cavities in the wall. When it hardened, it looked like shaving cream. Unfortunately, the insulation released formaldehyde as it cured and as it aged. Many people were forced to remove the insulation from their homes.

Health effects from short-term exposure to formaldehyde include skin rashes and irritation of the eyes, nose and throat.


Asbestos is the commercial name for a family of minerals that separate into dust fibres when crushed. When the fibres are inhaled into the lungs, the lungs cannot expel the fibres.

In the 1950’s and 1960’s, asbestos was commonly used for fireproofing (sprayed on steel beams in homes and businesses), heat insulation (on pipes, and on heating and venting ducts) and noise insulation (in ceilings and walls). In 1973, the use of asbestos as pipe and boiler insulation on heating systems was stopped. Thus, many older houses still have asbestos-containing material.

The simple presence of asbestos is itself not dangerous. The risk comes when the asbestos is disturbed and the fibres are released into the environment.

It is wise to periodically check materials (e.g. insulation) for signs of deterioration or disturbances. If a homeowner notices an asbestos containing material has been disturbed, a professional should be called to assess the situation. Do not vacuum or sweep up the material, as that will increase the number of air borne fibres released.

When doing renovations or repairs, homeowners should not disturb asbestos containing materials. A professional should be consulted on the proper removal.

It can be noted that no deaths due to acute asbestos exposure have been recorded. However, high levels of exposure in an occupational setting have been associated with numerous diseases.


Radon gas is a colourless, odourless radioactive gas that is produced from the natural breakdown of uranium. Radon is found in soils that are contaminated with certain types of industrial waste or in areas with localized uranium deposits.

When outdoors, radon is not considered a health hazard because the concentration is so small. However, in some homes, radon can build up. Approximately 0.1% of Canadian homes (1 in every 1000) have high levels of radon that require immediate action.

The radon gas enters the home by diffusing through dirt floors and tiny cracks in concrete walls, floor, basement drains and sumps. Concrete block walls are particularly susceptible to leakage.

The easiest way to reduce the exposure to radon gas is by increasing the ventilation in the home (e.g. opening windows), and sealing cracks and openings. If you suspect high levels of radon, spend less time in the basement because the radon is likely entering through the basement.

Radon shows no symptom of irritation and no early signs of exposure. While there is conflicting evidence, low levels of exposure may increase the risk of developing lung cancer, particularly for smokers. In addition, non-cancerous conditions such as emphysema, pulmonary fibrosis and pneumonia may results from acute exposure.

The location of small uranium deposits is unpredictable and localized. Low radon readings at a neighbours house do not guarantee low readings in your own home.