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Air Quality at Home

In industrialized countries, the average person spends about 90 per cent of his or her time indoors. Unfortunately, the air quality indoors is often two to five times worse than it is outdoors.

It is particularly important to keep the air inside your home as clean and fresh as possible. Your home’s building materials, furnishings and care products, in addition to the activities you do in your home, can all have an effect on the quality of the indoor air.

Contaminants of Indoor Air

There are many things in homes that can contaminate the air you breathe. The pollutants that affect human health can be biological, chemical or physical.

Biological contaminants are living organisms, such as:

  • Fungi, moulds
  • Dust mites
  • Bacteria
  • Animal dander

Chemical contaminants are gasses and particles that come from:

  • Furniture and carpets that emit volatile organic compounds (VOCs)
  • Tobacco smoke
  • Combustion by-products (furnaces, stoves, fireplaces)
  • Chemicals from cleaners
  • Paints, solvents and glues
  • Perfumes and fragrances
  • Pesticides
  • Plastics and polyvinyl chloride (PVC)
  • Lead (old lead paint, lead pipes)
  • Asbestos

Physical contaminants include:

  • Electromagnetic radiation
  • Radon gas
  • Heavy metals

To conserve energy, many homes built in the 1970s and 80s, and some remodelled homes, are well insulated and tightly built. Less fresh air can get in and the stale, contaminated air cannot escape. The levels of contaminants inside a home can build up until they are many times greater than the levels in outdoor air. This is why modern homes usually have heat recovery ventilators installed, and apartment buildings have heating, ventilating and air conditioning (HVAC) systems. This equipment conserves energy, but at the same time ensures an adequate supply of fresher, outside air.

Possible Health Effects

Common symptoms of exposure to poor indoor air quality include:

  • Headaches
  • Dizziness
  • Trouble concentrating
  • Fatigue
  • Eye dryness and/or irritation
  • Stuffy nose and/or sneezing
  • Sinus congestion
  • Sore throat and/or husky voice
  • Dry cough
  • Wheezing and/or shortness of breath
  • Nausea
  • Skin dryness and/or rashes

1. Biological Contaminants

Fungi and moulds grow on damp or wet surfaces that they can digest, such as paper, cardboard, drywall, leather, carpet and padded furniture. They can grow in humidifiers and heating, ventilating and air conditioning systems if the equipment is not properly cleaned and maintained.

Dampness and a good supply of human or animal dander encourage the breeding of dust mites.

2. Chemical Contaminants (Organic)

Volatile Organic Compounds
Volatile organic compounds (VOCs) are chemicals that are released into the air at room temperature. VOCs are given off by tobacco smoke, some glues, paints, solvents, some furniture, carpets, dry-cleaned clothes, cleaning products, air fresheners, moulds, mildew, fragrances, personal care products, and many other products commonly used indoors.

Some VOCs, such as formaldehyde and benzene, have been classified as carcinogens by the International Agency for Research on Cancer. Formaldehyde is a common component of particleboard, fibreboard, plywood, foam insulation, glues and fabrics. It can irritate the eyes and cause respiratory symptoms, such as stuffy nose, coughing and wheezing. Benzene can be found in a wide range of products, including glues, paints, furniture wax and detergents, as well as cigarette smoke. Benzene in the outdoor air comes from gas stations, motor vehicle exhaust and industrial emissions. This chemical can cause symptoms that range from mild to severe, even life-threatening.

Tobacco Smoke
Smoke from cigarettes, pipes, and cigars contains many pollutants, including gases, particulate matter and VOCs. According to the US Environmental Protection Agency (EPA), second-hand smoke is responsible for approximately 3,000 cancer deaths each year in non-smoking adults, and impairs the respiratory health of hundreds of thousands of children.

Combustion By-Products
As fuels are burned in furnaces, heaters, fireplaces, and stoves, contaminants can be released into the air in the home. These fuels include natural gas, wood, kerosene and oil, and incomplete combustion can lead to the release of particles and harmful gases, such as VOCs, nitrogen dioxide, sulphur dioxide and carbon monoxide.

3. Chemical Contaminants (Inorganic)

If your home was built before 1980, lead may be present in your plumbing and in the paint on the exterior of your home. If your home was built before 1960, the paint inside your home may contain lead. You may be exposed to lead through the drinking water, soil, paint and paint dust, and leaded glass. Lead pipes have been gradually replaced in municipalities, but sometimes the piping from the main municipal water lines to old homes, or the piping within the residence has not been replaced.

Lead poisoning can cause anemia and damage to the brain and nervous system. It is also extremely dangerous to the health of an unborn child.

Peeling or chipping paint that contains lead can be a serious health hazard. Make sure that it is repaired properly by trained people – scraping and sanding lead paint can spread toxic lead dust around.

To learn more, consult the Canada Mortgage and Housing Corporation’s Fact Sheet: Lead in Older Homes.

Prior to the 1960s, asbestos was used in insulation, fireproofing, wallboard, and ceiling and floor tiles. It was often mixed with a cement-like material and sprayed or plastered on ceilings and other surfaces. Now these materials may be crumbling and releasing asbestos. The tiny asbestos fibres are small enough to float in the air. They can then be inhaled and lodge in the lungs. Exposure to asbestos fibres can cause lung cancer and asbestosis, a chronic scarring of the lungs that hinders breathing.

Homes constructed in the 1960s and earlier have the potential for asbestos-containing floor tiles. Such resilient floor tiles are typically nine inches square and are stuck to the sub floor with a black mastic (gummy substance). Both the tiles and the mastic can contain asbestos.

4. Physical Contaminants

Electromagnetic Radiation
Some individuals have reported a variety of symptoms they associate with being near hydro towers, banks of computers or electrical appliances. Although short-term exposure to very high levels of electromagnetic radiation can be harmful to our health, there is limited evidence to confirm that exposure to low levels of electromagnetic radiation (from cell phones, for example) is harmful. Researchers continue to investigate a possible link between cancer and electromagnetic fields. The strongest evidence for possible harm exists for children; therefore, children’s use of cell phones should be limited.

Radon is a naturally occurring radioactive gas. It results from the radioactive decay of the element radium, found in rocks, soil and groundwater. It can enter a building through cracks in the foundation, dirt floors, basement drains and via well water. Radon sticks to particles in the air, and, if the particles are small enough, can be inhaled and lodge in the lungs. When the radon then undergoes its natural process of radioactive decay, it damages the lung tissue, and increases a person’s risk of developing lung cancer. The combination of smoking and exposure to radon may lead to a higher risk of lung cancer.

Radon is odourless and colourless. The only way to determine radon levels in your home is to test for it.

To learn more, consult the Canada Mortgage and Housing Corporation’s booklet Radon: A Guide for Canadian Homeowners.

What You Can Do

To help protect you and your family from potentially harmful toxic substances, here are some things you can do:

1. About Biological Contaminants

  • Stop leaks and clean up moisture immediately, to reduce the chance of mould growth.
  • Replace any porous materials that have been damaged by water, such as sheetrock, carpeting and upholstered furniture.
  • Remove clutter, especially from basements (moulds) and bedrooms (dust mites).
  • Keep pets out of the bedroom.
  • Wash bedding in hot (not warm) water weekly, to kill dust mites.

2. About Chemical Contaminants (Organic)

  • Reduce your exposure to VOCs by avoiding or removing as many sources from your home as possible, and by substituting less off-gassing (usually less odourous) materials or products. When painting, caulking or using cleaning materials, ventilate the area where you are using products that contain off-gassing VOCs.
  • Use a one-inch pleated filter in your furnace, rather than the usual flat surface filter. A pleated filter has more surface area to collect more dust particles. Remember to replace the filter regularly – as recommended by the manufacturer, or more frequently, especially if you have pets or are doing renovations.
  • Avoid indoor smoking.
  • If you have a gas stove, make sure your exhaust fan is functioning properly, and that you turn it on every time you use the stove.
  • Use environmentally safe cleaning products.
  • Open windows and use kitchen and bathroom exhaust fans if you use cleaning compounds, personal care products and other materials that give off VOCs.
  • When new furnishings are first brought into your home, make sure the area is well ventilated.
  • Choose solid wood or metal furniture when possible.
  • Choose sheets, blankets, curtains and other fabrics that are made of cotton and not treated with finishes to resist stains or wrinkles. If you do purchase treated fabrics, wash them thoroughly before storing them and air out before using them, to reduce the amount of VOCs you inhale.
  • Use a potpourri of dried flowers, herbs or citrus peels instead of synthetic air fresheners, if you wish to add fragrance to the air.
  • When renovating or painting, ensure that the area is sealed off, well ventilated and that you wear protective gear, such as a proper facemask, gloves and goggles.
  • Choose low-VOC paint, water-based urethane and other less toxic products when renovating.
  • If possible, consider alternatives to carpet, such as hardwood floors, ceramic tiles or cork flooring.
  • Avoid using pesticides indoors. Keep areas clean and dry. Use baits and less toxic products, such as borax or diatomaceous earth, if necessary.

3. About Chemical Contaminants

  • Never mix ammonia with bleach. The chlorine in the bleach reacts with the ammonia to produce a very hazardous gas.
  • If you are planning to renovate an old home that may contain lead paint, first consult the Canada Mortgage and Housing Corporation’s fact sheet on Lead in Older Homes.
  • If your drinking water goes through old lead pipes, be sure to run your water for two to three minutes in the mornings before using, and never use hot water from the tap for cooking. Water filters containing activated carbon can remove lead, but must be changed regularly according to the manufacturer’s suggestions.
  • To remove any materials in your home that contain asbestos, speak to your local health department or look in the Yellow Pages under Asbestos Abatement and Removal.

4. About Physical Contaminants

  • Keep a safe distance from microwaves, computers, bedside clocks and radios, and minimize cell phone use, while research proceeds on the health effects of electromagnetic radiation.
  • Have your home tested for radon and take remedial action if necessary. For more information on radon testing, see the Canada Mortgage and Housing Corporation booklet Radon: A Guide for Canadian Homeowners.


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