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Pollution & air quality

Indoor air quality

Your home

Your home should be safe and comforting, not a place that makes you sick. People can have air quality problems in any kind of home, new or old. The good news is that you can do something right now to improve your home's air quality.

Many things in your home can cause air quality problems. Learn more about these potential problems and how to solve them:

Common air quality problems in each room in your home
In the kitchen:
  • Moisture in the kitchen can be a source of mould and odours
  • Gas stoves or ovens release carbon monoxide, nitrogen oxides, and particulates
  • Pressed wood cupboards contain formaldehyde and can cause illness or irritation
  • Cleaning products often contain harsh chemicals that can be inhaled
In the living room:
  • New carpets can be a source of formaldehyde
  • Old carpets are a major source of dust, mold, and allergens, such as pet dander
  • Candles and incense can release lead and volatile organic compounds (VOCs), including particulate matter
  • Smoking releases toxic chemicals and gases that get trapped in the carpet, drapes, and furniture
In the bathroom:
  • Moisture and humidity from the shower can lead to mould
  • Chemical aerosols from personal care products and air fresheners
  • Many potentially harmful cleaning products are kept under the sink - check the labels
In the garage:
  • Car exhaust contains a host of chemicals and gases that can get into the house; don't run your car in the garage
  • Leaky gasoline containers can produce intoxicating or nauseating fumes
  • Improper storage of old paint cans or pesticides can release toxics and volatile organic compounds (VOCs)
In the basement:
  • Oil and gas furnaces can release carbon monoxide, if not properly maintained
  • Wood stoves can be a source of particulate matter, especially dust and soot
  • Stored paint cans and solvents are a prime source of VOC's
  • Cracked foundations can lead to a build up of radon in some homes
  • Leaky foundations can lead to mould and other biological contaminants
Healthy Home Audit

If you think that the air you breathe may be unhealthy, download the Lung Association's Healthy Home Audit to carefully diagnose your home's air quality problems.

Should I have the air in my home tested?

Testing for indoor air contaminants is possible, though not usually necessary. For example, if you see visible mould, it needs to be cleaned up. You then need to correct the problem (leaky pipe, excess moisture, etc.) that caused the mould to grow in the first place. If you notice a musty or mouldy odour in your home, trace it to its source and deal with the problem there.

You should remove obvious sources of contaminants as soon as possible, unless "before and after" documentation is required for medical and legal reasons. Testing can then be performed, if necessary, to pinpoint any residual contaminants that may be contributing to ongoing health problems.

If you or others in the home are experiencing symptoms which you feel are caused by something inside your home, check out The Lung Association's Healthy Home Audit (PDF) or visit, a website that takes you on a tour of a typical house and points out air quality trouble spots.

If you still can't find the sources of your symptoms, you may next want to consider air sampling by a qualified professional. Canada Mortgage and Housing Corporation (CMHC) has a list of trained Indoor Air Investigators; call CMHC at 1-800-668-2642 to see if there is an investigator in your area. Or, check the yellow pages in your phone directory under 'Environmental Consultants' to see if indoor air quality services are available. Ask about the consultant's training. Inquire what they base their analysis on and if you will be provided with a written report. Ask for references and contact the Better Business Bureau.

Carpets, old and new

Carpets, underpadding and adhesives are all part of your floor covering and may affect air quality indoors. Carpets may be a source of both chemical and biological pollution in your home. Carpets emit a variety of volatile organic compounds (VOCs), gases which are emitted at room temperature. One of these, 4-phenylcyclohexene (4-PC) is primarily responsible for the odour associated with new carpet installation. Other VOCs detected in carpet emissions include styrene, toluene, formaldehyde, a variety of benzenes and many others. The cushion and adhesives are also sources of emissions. During the manufacturing process chemicals such as dyes, pesticides, fungicides, fire retardants and anti-stain coatings are added. These additives are frequently released into the air indoors.

Carpets also act as a "sink" for chemical and biologic irritants. In other words, they collect airborne pollutants and substances that may be spilled or tracked in from the outdoors. As well, studies have found that biologic irritants such as bacteria, mites and fungi are commonly found in carpets. Removing a carpet that has been in place for a long time can be a sobering experience, when we see and smell the pollutants in and under it.

Health effects of carpets

The chemical emissions from carpets may be responsible for a variety of adverse health effects including eye, nose and throat irritations, allergy or flu-like symptoms, and fatigue. Often these effects occur during or immediately after the installation of carpets.

Allergic reactions may be the most common health problem associated with biologic irritants and carpet. These reactions can range from mildly uncomfortable to life threatening, as in a severe asthma attack. Some common signs and symptoms are a runny nose and sneezing, coughing, wheezing and difficulty in breathing, headache, fatigue and watery eyes. Little information exists about the possible long-term health effects of exposure to these chemical and biological contaminants.

Parents should avoid letting their babies and toddlers crawl on new or dirty carpets since they risk breathing in full doses of biological and chemical contaminants.

What you can do about the possible problems with carpets

New Carpet Installation

  • When getting rid of your old carpet, vacuum it before removal to minimize the release of pollutants. Then, using a wet mop, clean up all the debris that has worked its way through the carpet.
  • Ask your retailer for low chemical emission carpet, cushion and adhesives. You can test your new carpet by placing a sample in a clean and tightly sealed jar and leaving it on a sunny window sill for a day. Upon opening a strong smell will identify problem carpets.
  • Ventilate properly. Where possible, open windows during and after the installation of new carpet. One window should open into the wind and one should open away from the wind. Operate your ventilation system at maximum outdoor air during and after installation for at least 48 to 72 hours.
  • Consider leaving the premises during and immediately after installation. Try to schedule the installation when most family members will be away, such as a long weekend.

Care of Old Carpets

  • Keep carpets clean and dry. Regular vacuuming can keep your carpet relatively dry and clean. If you're in the market for a new vacuum cleaner, you could get one with a HEPA (High Efficiency Particulate Arrestance) filter, which removes over 99% of dust on vacuumed surfaces. A central vacuum system is also highly effective.
  • When cleaning, use only nontoxic carpet cleaners and follow the manufacturer's directions carefully. If the product label includes a caution or toxic symbol, or if the odour is strong, choose another product. Allow carpet to dry fully after wet cleaning.
  • Think before shampooing your carpet. People who misread or fail to follow directions for diluting carpet shampoo may expose themselves and others to respiratory problems from soap dust. Soap dust will lead to coughing, dry throat, breathing difficulties, nasal congestion and headaches. Vacuuming will not remove the dust. Steam cleaning is the only effective means to remove the dust and solve the problem.
  • Clean spills promptly and thoroughly.
  • If your carpet is water damaged and mouldy it should be discarded. Beware of anti-mould treatments; they may be more dangerous to your health than the mould being removed.
Humidity - not enough
The air in my home feels dry. Should I install a humidifier?

Before installing a humidifier, buy a hygrometer (humidity measuring device) to measure your indoor humidity. You can buy a hygrometer at an electronic specialty store or a hardware store.

If the winter humidity is less than 30% Relative Humidity (R.H.), a humidifier may be helpful. There are a couple of things you should keep in mind, though:

  • the reason for extremely low humidity is often air leaking through the walls of your home. If you load up the interior with more moisture than the wall can handle, you may generate condensation and ultimately mould growth in the walls. Tightening your home up by sealing cracks is often a better alternative.
  • if windows are showing winter condensation on the interior, the humidity is already higher than the house can handle. Canada Mortgage and Housing Corporation (CMHC) advises keeping winter indoor humidity lower than 45% R.H.. Whatever the season, CMHC recommends humidity be kept low enough that window condensation does not occur. We recommend a RH of 30 - 50% maximum for most of the year, because too much humidity can promote mould growth.
  • If you notice condensation on your windows, consider replacing them with double pane windows, and getting an energy analysis of your home. Meanwhile, use the window condensation as an indicator that the humidifier needs to be turned down, or that your home needs more fresh air ventilation
Humidity - too much
The air in my home feels too moist, especially in the basement. Should I install a dehumidifier?

When household humidity levels exceed 60% Relative Humidity, there is a danger of encouraging growth of dust mites and mould growth. Buy a hygrometer, a humidity measuring tool (available from electronic specialty stores or hardware stores), and measure exactly what humidity levels you are dealing with in various parts of the home.

In most parts of the country, it's a good idea to keep a dehumidifier in the basement and to run it, especially in hot and muggy weather. Insulating cold water pipes and toilet tanks will also help to avoid condensation and water dripping during a humid summer season.

Pesticides indoors

Pesticides are chemical or biological substances used to destroy living things such as: insects (insecticides), plants (herbicides), termites (termicides), rodents (rodenticides) and fungi (fungicides). They are sold most commonly as sprays, liquids, sticks and powders.

Pesticides are a problem whenever they are used indoors. Besides their immediate toxicity, many pesticides stick around after their initial application. This means you continue to breathe them in long after they are applied. For example, chlordane, which was used for termite and carpenter ant control and is now banned, may last for over twenty years.

In some cases, people may be unaware that pesticides are being applied in their residence. Exposure to pesticides occurs through skin contact, by ingestion or by inhalation. They can enter your home in a variety of ways:

  • through direct indoor application
  • through application to humans and pets for head lice, flea, and tick control
  • by storing pesticides inside your home
  • through the use of pesticides outside the home
  • by bringing in shoes, clothing and other objects and pets contaminated by pesticides
  • through building materials and furnishings such as pressure treated lumber, carpets, wallpaper adhesives and moth balls
Health effects of pesticides indoors

Pesticides are a concern because they cannot be adequately tested for long-term adverse health effects on humans. Nor can the mix of chemicals to which we are exposed or the varied responses of humans be replicated under laboratory conditions. It stands to reason that if pesticides can kill pests, then pesticides may also harm us. Pesticides are a broad category of complex chemicals which may cause many immediate and long term negative health effects. These include:

  • mild symptoms such as headaches, fatigue and shortness of breath
  • serious reactions like vomiting and loss of consciousness
  • long term adverse effects on behaviour, the nervous, immune and endocrine systems
  • forms of cancer such as non-Hodgkins lymphoma, leukemia, and soft tissue sarcoma

There are approximately 1,200 ingredients registered for use in pesticide formulations, some of which (e.g. lindane used in shampoo for head lice) are suspected carcinogens.

What you can do about pesticides indoors

The best way to avoid indoor air pollution from pesticides is to not use them at all. The alternative is to implement an integrated pest-management program, with the most important element being prevention.

  • Keep window screens in good repair.
  • Store wood outside, away from the house.
  • Keep foundation shrubbery and other plants at least two feet away from the house.
  • Identify cracks and other openings which act as entry points for pests into your home and seal these areas with caulking or foundation fill.
  • If you have trouble with rodents use steel wool or traps where they enter your home.
  • Store food in covered containers, not bags.
  • Keep surfaces free of food residues and do not leave trash or food out overnight or for extended periods of time. As well, keep garbage and clutter away from the outside of your home to avoid attracting rodents and insects.
  • Ants can be dissuaded from entering a home by sprinkling cayenne pepper across their point of entry.
  • You can catch most crawling insects with pesticide-free glue traps available at hardware stores.
  • Correct indoor moisture problems which encourage pests such as silverfish, carpenter ants, and earwigs.
  • Give your pet oral flea and tick prevention medication.
  • Teach your children not to share combs, brushes, or head gear.
Caution against pesticides:

The Lung Association strongly advises against the use of pesticides. In situations where their use is out of your control, landlords are required to give seven days notice to enact regular repairs and twenty four hours notice to enter your premises for an inspection. Therefore, try to persuade the landlord ask for a pesticide-free treatment (such as glue traps) from the pest management company. If all else fails, and your apartment is to be sprayed:

  • Put all food in sealed containers, or the fridge.
  • Evacuate your home for a minimum of 24 hours.
  • When you return, air thoroughly and wash all dishes and cutlery, bedding, upholstery, carpets, etc.
Biologic irritants

Biological irritants are things that are, were once, or come from living organisms. Some common biological irritants are:

  • bacteria
  • pollen
  • viruses
  • animal dander (tiny scales from hair, feather, or skin)
  • fungi
  • dust mites and other insects
  • mould

Biologic irritants contribute to poor indoor air quality and may be a major cause of days lost from work or school, and of doctor and hospital visits. Biologic irritants are often invisible and when airborne can be inhaled into your lungs. Some biologic irritants can even damage surfaces inside and outside your house.

Biologic irritants need two things to grow: nutrients and moisture. Around your home, sources of biologic irritants include:

  • bathrooms
  • damp or flooded basements
  • appliances such as humidifiers, dehumidifiers and air conditioners
  • mattresses, carpets and furniture

Decreased ventilation may increase problems with biologic irritants around your home.

Health effects of biologic irritants

We are all exposed to biological irritants and have evolved to survive low exposures. Adverse health effects from biologic irritants depend on the type and amount of irritant and on individual sensitivities.

Allergic reactions may be the most common health problem associated with biological irritants. They are often related to animal dander (mostly from dogs and cats), dust mites and pollen. Reactions can range from mildly uncomfortable to life-threatening, as in a severe asthma attack.

Some common signs and symptoms of a reaction to a biologic agent include:

  • runny nose, sneezing and watery eyes
  • coughing, wheezing and difficulty breathing
  • headache and fatigue

People with asthma are especially susceptible to allergic problems caused by biologic irritants. They have very sensitive airways that react to allergens and irritants, making breathing difficult.

Viruses and bacteria that cause disease are another kind of biologic irritant. Indoor air may contain germs that cause the flu, measles, chicken pox, tuberculosis and other diseases. Crowded homes with poor air circulation promote the spread of germs.

Toxic reactions are the least studied and least understood problems associated with biologic irritants. Some research suggests that toxins related to biologic irritants can damage a variety of organs and tissues in the body, including the liver, the central nervous system, the digestive tract and the immune system.

What you can do about biologic irritants in your home

Before you give away the family pet or move, there are less drastic steps that can be taken to reduce potential problems. Proper cleaning and maintenance can help reduce problems with biologic irritants.

The following solutions will really help. People living with asthma or allergies may need to do these things and more:

  • Control moisture: Use exhaust fans in bathrooms and kitchens to vent moisture to the outside (not into the attic). Vent your clothes dryer to the outside. Pay special attention to carpets on concrete floors: carpets can absorb moisture and serve as a place for biologic irritants to grow. Avoid adding excess moisture to your home. Ideal humidity levels are between 30% and 50% relative humidity. You can buy a hygrometer (humidity meter) to measure levels.
  • Maintain home appliances: Have major appliances such as furnaces, heat pumps, and central air conditioners, inspected and cleaned regularly by a professional. Window or wall air-conditioning units, if improperly maintained, may also become a source of biologic irritants. Humidifiers are unnecessary in most homes. If you use one, be sure to empty its tank every day or according to manufacturers instructions.
  • Clean surfaces: Keep moist surfaces such as bathtubs, shower stalls and kitchen counters clean. Remove mouldy shower curtains and scrub well with a household cleaner and rinse before hanging them. Clean mould from walls, ceilings, floors and paneling. Do not simply cover mould with paint, stain, varnish or a moisture-proof sealer, as the mould may resurface.
  • Dust control: Controlling dust is very important for people who are allergic to animal dander and mites. Dust mites thrive in locations with higher humidity, such as mattresses, sofas, curtains, and carpets. Always wash bedding in very hot water every week to kill dust mites. Keep carpets clean and dry. Regular vacuuming can keep your carpet relatively clean. If you are in the market for a new vacuum cleaner, you could get one with a HEPA (High Efficiency Particulate Arrestance) filter which removes over 99% of dust on vacuumed surfaces. A central vacuum system is also highly effective.
  • Ventilation: Ventilation is a necessary requirement in healthy houses and can help stop moisture problems if sources of biologic irritants are also under control.
What to do if you find mould in your home

If you find mould in your home, assess the damage. People can usually clean small and moderate amounts of mould themselves; larger amounts of mould should be removed by a professional. Follow these directions on how to clean up mould, from Canadian Mortgage and Housing Corporation (CMHC).

Carbon Monoxide

Carbon Monoxide (CO) is a colourless, odourless gas that is produces as a result of incomplete burning of carbon-containing fuels. Many Canadians die every year and thousands of others become ill or need medical attention from carbon monoxide poisoning related to residential combustion appliances.

Any fuel-burning appliance that is not adequately vented and maintained can be a potential source of CO, including:

  • fireplaces, wood and coal stoves, space heaters
  • gas appliances (furnaces, ranges, ovens, water heaters, clothes dryers, etc.)
  • charcoal grills, camp stoves
  • automobile exhaust fumes
  • gas-powered lawn mowers and tools
  • power tools
  • cigarettes and second-hand smoke
Health effects of carbon monoxide

Carbon monoxide exposures especially affect unborn babies, infants and people with anemia or a history of respiratory or heart disease. Breathing in low levels of CO can cause fatigue and increase chest pain in people with chronic heart disease.

Breathing in higher levels of carbon monoxide causes flu-like symptoms such as:

  • headaches
  • dizziness
  • weakness
  • sleepiness
  • nausea
  • vomiting
  • confusion
  • disorientation.

At very high levels, carbon monoxide causes loss of consciousness and death.

What you can do about carbon monoxide

Preventing carbon monoxide poisoning from exposure to dangerous levels of carbon monoxide in the home is possible by taking some simple steps:

  • Make sure appliances are installed and working according to manufacturers' instructions and local building codes.
  • Have only a qualified technician (WETT certified) install or convert fuel-burning equipment from one type to another.
  • Have the heating system, chimney and flue inspected and cleaned by at least once a year by a technician certified under the Wood Energy Technical Training (WETT) Program or, in Quebec, the Association des professionnels du chauffage (APC).
  • Do not use ovens and gas ranges to heat your home.
  • Do not burn charcoal inside a home, cabin, recreational vehicle or camper.
  • Do not operate gasoline-powered engines in confined areas such as garages or basements.
  • Never leave your car or mower running in a closed garage.
  • Make sure your furnace has adequate intake of outside air.
  • Choose vented appliances whenever possible.
  • Use kerosene space heaters and unvented gas heaters only in well ventilated rooms.
  • Install a carbon monoxide detector with an audible alarm in your home and garage. CO detectors should meet Cansdian Standards Association (CSA) standards; have a long-term warranty; and be easily self-tested and reset to ensure proper functioning. For maximum effectiveness during sleeping hours, carbon monoxice detectors should be placed as close to sleeping areas as possible.