A healthy indoor environment means keeping two types of contaminants out of your air;
chemical and biological contaminants.
Chemical contaminants can be either gases (e.g., carbon monoxide, nitrogen dioxide) or
particles (e.g., aerosol, soot). Some common household sources of chemical contaminants
include oil and gas appliances, tobacco smoke, paints, and pesticides. Biological
contaminants originate from living things or are themselves living things. These
contaminants can also be either gases or particles (e.g., mould spores). Sources of
biological pollutants include humidifiers, air conditioners, mattresses, pets, and
If you suspect that you have an indoor air quality problem, you may want to begin by
undertaking a home audit. Begin an audit by first taking a walk around the outside of your
home. A quick assessment of your home's overall condition will help you identify problems
that can allow both chemical and biological contaminants to get indoors. Some things to
look out for are cracks, blockages, and problems with eavestroughs and downspouts.
Cracks in your homes outer walls allow moisture to get in and provide a perfect
environment for the growth of biological contaminants such as mould. Cracks are also entry
points for insects and rodents. Blockages of vents, air intakes, and chimneys prevent the
proper operation of your home systems (e.g., furnace, heat recovery ventilator). These
systems are an essential part of keeping your indoor air clean. If you see any blockages
(e.g., leaves, nests), remove them. Look out for and fix any holes in your eavestroughing,
and check to make sure that your downspouts are draining well away from your home. Poor
drainage can cause moisture to seep inside your home, which can contribute to biological
Odours in your home are an indicator of poor air quality. To eliminate them, find the
source of the problem (e.g., rotting vegetables) and remove it. In addition, make sure
that bathroom and stove fans are used regularly while cooking. They should also be
exhausted to the outside and cleaned on a regular basis. Consider reducing your use of, or
getting rid of, hazardous household and personal care products, such as hair spray, air
fresheners, polishes, waxes and pesticides. These common household products can be
hazardous to your health, since many of them contain toxic chemicals. Even if you were to
store these products in your basement, chemicals released from them can still get into the
air in other areas of your home.
Musty, damp, or earthy odours are a good sign that you may have a problem with
biological contaminants, such as mould. Some visible signs of moisture problems include:
black, white, or multicoloured discolourations on the walls, ceiling, or floors; wet or
damp floors or walls; condensation on the windows; and white, powdery stains on exposed
concrete walls or floor.
To eliminate mould, keep all surfaces clean and dry. Use a vented exhaust fan in the
kitchen and bathroom. When cooking, don't let liquids and food simmer uncovered for too
long, as this is an easy way for moisture to accumulate. If you do have visible mould,
remove it with a solution of one part bleach and two parts water and a small amount of
dishwashing detergent (make sure you wear gloves, a mask and have good ventilation).
Other things you can do to reduce moisture in your home are:
Relocate downspouts away from the
foundation of your house
Use a dehumidifier
Dispose of any water damaged
articles (e.g., books, carpets, boxes).
Disconnect or remove furnace humidifiers because they
can distribute high levels of biological contaminants throughout your home
You should also regularly maintain and inspect all your major household devices, such
as your furnace, air conditioners and wood stoves. Leaks from poorly installed and poorly
maintained furnaces, dryers, and water heaters can release hazardous pollutants (e.g.,
carbon monoxide, nitrogen dioxide) into your air. Poorly maintained air conditioners
provide ideal breeding conditions for micro-organisms (e.g., bacteria, mould). These
micro-organisms are readily blown from the machines coils and filters into the room,
where they may contaminate the air.
Environmental Tobacco Smoke (ETS), the exhaled smoke and smoke from the burning end of
cigarettes, is a serious indoor air contaminant that often produces levels of carbon
monoxide and other toxins well above accepted standards for human exposure. Besides
breathing in ETS, you are also exposed to these harmful chemicals long after smoking ends.
This is because these chemicals are absorbed by drapes, linens, furniture, and clothes,
and are re-emitted back into the air you breathe.
If you have recently purchased carpeting, drapes, or stuffed furniture, you may want to
keep in mind that they can release chemical contaminants, such as formaldehyde. Over time,
they may also become a source of biological contaminants (e.g., dust mites, mould, and pet
dander) as they collect moisture, dirt, and debris. Before purchasing new furnishings,
consider buying furniture made of solid wood. Veneers and pressboard often contain
formaldehyde, benzene, or xylene.
The presence of dust in the air is natural; you can never get rid of all of it. But it
can be a source of indoor air quality problems. The best you can do is control it - both
at the source and by cleaning regularly (at least once a week) with a damp cloth. Dust
mites (tiny insects that live off the bits of skin we shed all day) can be the result of a
dust problem. Symptoms of exposure to dust and dust mites include coughing and wheezing,
shortness of breath, and chest tightness.