Combustion pollutants are gases or particles that come from burning materials. Combustion pollutants found indoors include: outdoor air, tobacco smoke, exhaust from car and lawn mower engines, and pollutants produced by some hobby activities such as welding, woodburning, and soldering.

Combustion pollutants can also come from vented or unvented combustion appliances such as space heaters, gas ranges and ovens, furnaces, gas water heaters, gas clothes dryers, wood or coal-burning stoves, and fireplaces. The types and amounts of pollutants produced depend upon the type of appliance, how well the appliance is installed, maintained, and vented, and the kind of fuel it uses.

The most common fuels used in these appliances are natural or LP gas, fuel oil, kerosene, wood, or coal. Some of the common pollutants produced from burning these fuels are carbon monoxide, nitrogen dioxide, particles, and sulfur dioxide. Other pollutants produced by some appliances are unburned hydrocarbons and aldehydes.

Combustion always produces water vapor. Water vapor is not usually considered a pollutant, but it can result in high humidity and wet surfaces -- conditions which encourage the growth of dust mites, mold, and bacteria.

Breathing high levels of nitrogen dioxide causes irritation of the respiratory tract and causes shortness of breath. Compared to healthy people, children, and individuals with respiratory illnesses such as asthma, may be more susceptible to the effects of nitrogen dioxide.

Some studies have shown that children may have more colds and flu when exposed to low levels of nitrogen dioxide. When people with asthma inhale low levels of nitrogen dioxide while exercising, their lung airways can narrow and react more to inhaled materials.

Sulfur dioxide at low levels of exposure can cause eye, nose, and respiratory tract irritation. At high exposure levels, it causes the lung airways to narrow. This causes wheezing, chest tightness, or breathing problems. People with asthma are particularly susceptible to the effects of sulfur dioxide. They may have symptoms at levels that are much lower than the rest of the population.

Proper selection, installation, inspection and maintenance of your appliances are extremely important in reducing your exposure to combustion pollutants. Providing good ventilation in your home and correctly using your appliance can also reduce your exposure. Additionally, use of residential carbon monoxide detectors can reduce the risk of death due to carbon monoxide poisoning.

Here are some guidelines to follow when selecting combustion applicances:

• Choose vented appliances whenever possible.
  
• Only buy combustion appliances that have been tested and certified to meet current safety standards. Examples of certifying organizations are Underwriters Laboratories (UL) and the American Gas Association (AGA) Laboratories. Look for a label that clearly shows the certification.
  
• All currently manufactured vented gas heaters are required by industry safety standards to have a safety shut-off device, which helps protect you from carbon monoxide poisoning.
  
• If you are considering the purchase of an unvented space heater, check local and state building codes and fire ordinances to see if you may use one.
  
• If you must replace an unvented gas space heater with another, make it a new one. Heaters made after 1982 have a pilot light safety system called an oxygen depletion sensor (ODS), which shuts off the heater when there is not enough fresh air. Look for the ODS label; older heaters will not have this system.
  
• Consider buying gas appliances that have electronic ignitions rather than pilot lights. They are more energy-efficient and less polluting.
  
• Buy appliances that are the correct size for the area you want to heat. Using the wrong size heater may produce more pollutants in your home and is not energy-efficient. Talk to your dealer to determine the type and size of appliance you need, or write to the appliance manufacturer for more information.
  
• All new woodstoves are EPA-certified to limit the amounts of pollutants released into the outdoor air. For more information on selecting, installing, operating, and maintaining woodburning stoves, write to the EPA Wood Heater Program (click link below for booklet with address).
  
• Before buying a woodstove check your local laws about the installation and use of woodstoves. Make sure your wood stoves is properly installed, operated, and maintained to reduce leakage of by-products and to lower the risk of house fires. Click the link below for tips on using your wood stove safely.

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