Indoor air quality

Indoor air quality is an area of increasing concern in the United States. While most people are aware of the threat posed by outdoor air pollution (such as smog), few realize that inside homes, schools and offices one can be exposed to two to five times as many pollutants as outdoors, according to the U.S.Environmental Protection Agency. Indoor air pollution has been ranked as oneof the top five environmental risks to public health by the EPA and its Science Advisory Board. In addition, the U.S. Occupational Safety and Health Administration has estimated that 30 percent of Americans who work in non-industrial buildings are exposed to indoor air pollution.

During the 1970s energy crisis, buildings were designed to be airtight, conserving as much warm air during the winter and cooled air during the summer aswas possible. Windows that could not be opened became a common part of building design. Ventilation systems were altered from past practice as well. Rather than drawing in large amounts of fresh air from the outside and put in theeffort and expense of heating or cooling it, the new systems drew in relatively little outside air and instead recirculated indoor air. These energy-conserving features became widely used in the designs of office buildings, shopping centers, schools and homes.

It is now clear that such airtight buildings create problems. Because of inadequate ventilation to the outside, the air pollutants inside the buildings are neither diluted or removed. The results can range from nose, eye and throatirritation and aggravation of asthma to an increased risk of lungcancer.

Where do these pollutants come from?

• Some pollutants come from outsidesources. These include pesticides, outdoor pollution, and radon. Radon is anaturally occurring gas that is given off as a byproduct of the decay of theelement uranium. Uranium is present is many types of soil and rock, especially phosphate, granite and shale. If rock or exposed soil is present in the basement of a building, radon can leach into the air inside the basement. If inhaled, its radioactive particles can become trapped in lung tissue and lead, possibly, to lung cancer.
• Building materials and furnishings can add to indoor air pollution. Among these products are asbestos-based insulation, carpet adhesives, and furniture or cabinets made from pressed wood that uses certain types of adhesives.
• Combustion sources are also sources of indoor air pollution. These include oil, gas, coal and wood burned for heat or used in cooking, and also tobacco products. As they burn, these materials release carbon monoxide (CO), a colorless and odorless gas that can be fatal in high concentrations. People are often exposed to CO by improperly adjusted gasstoves, cars left idling inside a closed, attached garage, and from tobaccosmoke. Tobacco smoke, in addition to carrying CO, carries more than 4,000 substances, of which more than 40 have been known to cause cancer.
• Biological sources of indoor air pollution include mold, mildew, fungi andbacteria (which are found in areas with high moisture levels such as bathrooms), dust mites and animal dander.
• Common household products add to the problem of indoor air pollution. Cleaning products and air fresheners, personal care products such as hair sprays, paint strippers and paints, and glues can all linger in the air long after they have been used.

Exposure to small amounts of indoor air pollutants can cause minor irritations, such as dry, scratchy eyes and throats, or headaches. However, in large concentrations pollutants can lead to dizziness, tiredness, and nausea, and rashes. Each year there are news reports of buildings being evacuated because of "sick building syndrome," a group of health symptoms listed above that stem from poor air quality inside a building and usually subside after leaving the building. Long-term exposure to some indoor airpollutants can lead to damage of the central nervous system, kidneys and liver.

Although anyone can have problems because of indoor air pollution, most susceptible are children, the elderly, and people who have respiratory ailments such as bronchitis, asthma or emphysema.

Adequate ventilation goes a long way in eliminating problems with indoor airpollution, as does controlling the humidity in a building. Other steps to take to maintain the quality of air inside your home, office or school include:

• Do not allow anyone to smoke inside the building, whether cigarettes,pipes or cigars.
• Be sure that gas stoves and other gas appliances areproperly adjusted and in proper working condition.
• Do not idle yourcar in the garage.
• Have a professional inspect, clean and tune up home heating systems each year.
• Test your home for radon with a radon test kit, which can be purchased at hardware stores and home centers.
• Regularly clean air conditioners, humidifiers and dehumidifiers to control thegrowth and spread of mold and milder spores.
• Vacuum often to controlpet dander and dust mites (it's best to use a vacuum cleaner equipped with ahigh-efficiency particulate air filter for the job).
• Keep indoor moisture between 30 and 50 percent to control the growth of mold and mildew.

If you feel consistently better after you leave a certain building, whether your home, school or office, you might have reason to suspect a problem with the air quality.

For more information, you can contact the EPA's Indoor Air Quality Information Clearinghouse, which is available Monday through Friday, 9 a.m. to 5 p.m. Eastern time, at 800-438-4318. Other sources of information include the National Radon Information Hotline (1-800-644-6999) and the National Hispanic Indoor Air Quality Hotline (1-800-725-8312).