People tend to think of air pollution as something that happens 'outside'. But even in the most industrialized cities, the air inside many buildings and homes is often more polluted than outdoor air. To make matters worse, research shows that people now spend approximately 90% of their time indoors.
Inside air can be contaminated by infiltration from outside sources. For example, fine particulate matter from smoke or vehicle exhaust is so tiny it easily infiltrates homes through openings and even directly through the walls. Serious indoor pollution can occur in airtight homes when ventilation intake vents are near smoke or exhaust sources.
Unfortunately, cigarette smoke still tops the list for damaging pollution exposures. The choice to smoke inside is indefensible given the profound suffering and loss of health and life from first and second hand smoke. The good news is that removing this inside source is usually a fairly simple matter.
Any combustion sources inside is a potential sources of indoor air pollution. Appliances that burn, for example, oil, gas, kerosene, coal, or wood need to be maintained in top working order. Gaseous and particulate pollution can also come from chimneys and flues that are improperly installed or maintained and cracked furnace heat exchangers.
Poor draft is a common problem in wood stove systems that can result in a "back-draft" of smoke and carbon monoxide every time the stove door is opened. Back-draft contaminants can also escape during operation if door and window gasket seals are damaged.
Bringing natural gas inside the home and burning it are significant sources of indoor chemical contaminants. Exposures can be minimized from gas stoves, for example, by using a good fume hood that vents upwards and outside; adjusting the burners so the flame tip is blue, not yellow; and using pilotless ignition.
Starting and stopping a car in an attached garage, even with the door wide open, results in emissions of various chemicals that can be drawn into the house over a period of hours. For example, there are measurable concentrations of benzene in homes with attached garages. After a car has left, carbon monoxide levels in the house can climb to levels that will set off a CO alarm. Exposures can be minimized by venting contaminated air outside, and by ensuring that the garage is airtight.
There are many non-combustion sources of indoor air pollution including mould, dander, pressed wood products, building materials, furnishings, carpets, household products like air fresheners, and even some air cleaners that produce damaging charged particles and ozone when operating.
Your home is your castle. Have a look around and make sure your air is safe and clean from the inside out.
The Canadian Mortgage and Housing Corporation Clean Air Guide, (revised in 2006)
Health Hazards of Natural Gas
Radon Infiltration, Second Leading Cause of Lung Cancer
EPA - Indoor Air Quality, Residential Air Cleaners
Health Canda - Indoor Air Pollution