Combustion products are produced when something burns. Major indoor combustion pollutants include carbon monoxide (CO), nitrogen dioxide (NO2), polycyclic aromatic hydrocarbons (PAHs), and both fine (PM2.5) and ultrafine particles (UFP). These pollutants result from burning-related activities in the home, including gas appliances and stoves, grills, motor vehicles running in attached garages, and the burning of wood, candles, tobacco, marijuana, and incense. Combustion products can also move indoors from outdoor air.
The two strategies for reducing exposure to combustion products in homes are source control (to reduce the amount of pollutant produced) and improved ventilation (to remove any existing pollutants from the home).
Avoid operating fuel-burning unvented space heaters. Take special precautions if you must do so.
- Use proper fuel and keep heater properly adjusted (avoid yellow-tipped flame).
- Open a door from the room where the heater is located to the rest of the house and open a window slightly.
Install and use exhaust fans over gas cooking areas and keep burners properly adjusted.
- Use a stove hood with a fan vented to the outdoors.
- Check that flames in gas stoves are properly adjusted (avoid yellow-tipped flame).
- Use new stoves that rely on pilot-less ignition to prevent continuous gas burning.
- Never use a gas stove to heat your home.
- Always confirm the flue in your gas fireplace is open when it in use.
Use proper manufacturer guidelines to minimize woodstove emissions. New stoves should have EPA emission certification.
- Door in old woodstoves should be tight-fitting.
- Use aged or cured (dried) wood only.
- Follow the manufacturer's directions for starting, stoking and putting out the fire.
- Do not burn pressure-treated wood – it releases toxic gases.
Increasing Outdoor Ventilation
Using ventilation to reduce indoor air pollutants increases the amount of outdoor air brought indoors. (Note that most current central forced air heating and air-conditioning systems in homes do not bring in any outdoor air, but just recirculate the indoor air.) However, with polluted outdoor environments, such as in some urban areas, bringing in more outdoor air may increase the amounts of some pollutants indoors. A decision on whether to open windows (or increase ventilation by a central mechanical ventilation system) depends on the need to ventilate the indoors and, to some extent, the outdoor air quality. Very often the most effective way to improve indoor air quality is to eliminate individual sources of indoor pollution or reduce their emissions, rather than to increase outdoor air ventilation.
The California Air Resource Board has general information about combustion pollutants and specific information about combustion products in your home.
The US EPA has further information on combustion products and indoor air quality, as does the World Health Organization.