Conditions: radon, carbon monoxide, nitrogen dioxide, formaldehyde, asbestos, pesticides
Source: NWHIC


What are common indoor air pollutants?
What are common health effects of indoor air pollution?
What can I do to my home to reduce indoor air pollution?

See also...

What are common indoor air pollutants?

Radon, environmental tobacco smoke, biologicals, carbon monoxide, nitrogen dioxide, organic gases, respirable particles, pesticides, formaldehyde, and asbestos.


Sources: Earth and rock beneath home; well water; building materials.

Levels in Homes: Based on a national residential radon survey completed in 1991, the average indoor radon level is 1.3 picocuries per liter (pCi/L). The average outdoor level is about 0.4 pCi/L.


Sources: Invented kerosene and gas space heaters; leaking chimneys and furnaces; back-drafting from furnaces, gas water, heaters, woodstoves, and fireplaces; gas stoves, automobile exhaust form attached garages, and environmental tobacco smoke.

Levels in Homes: Average levels in homes without gas stoves vary form 0.5 to 5 parts per million (ppm). Levels near properly adjusted gas stoves are often 5 to 15 ppm and those near poorly adjusted stoves may be 30 ppm or higher.


Sources: Cigarette, pipe, and cigar smoke

Levels in Homes: Particle levels in homes without smokers or other strong particle sources are the same as, or lower than, those outdoors. Homes with one or more smokers may have particle levels several times higher than outdoor levels.


Sources: Kerosene heaters, invented gas stoves and heaters, and environmental tobacco smoke.

Levels in Homes: Average level in homes without combustion appliances is about half that of outdoors. In homes with gas stoves, kerosene heaters, or invented gas space heaters, indoor levels often exceed outdoor levels.


Sources: Wet or moist walls, ceilings, carpets, and furniture; poorly maintained humidifiers, dehumidifiers, and air conditioners, bedding, and household pets.

Levels in Homes: Indoor levels of pollen and fungi are lower than outdoor levels (except where indoor sources of fungi are present). Indoor levels of dust mites are higher than outdoor levels.


Sources: Household products including: paint, paint strippers, and other solvents; wood preservatives; aerosol sprays; cleansers and disinfectants; moth repellents and air fresheners; stored fuels and automatize products; hobby supplies; and dry-cleaned clothing.

Levels in Homes: Studies have found that levels of several organic average 2 to 5 times higher indoors than outdoors. During and for several hours immediately after certain activities, such as paint stripping, levels may be 1,000 times background outdoor levels.


Sources: Fireplaces, woodstoves, and kerosene heaters and environmental tobacco smoke.

Levels in Homes: Particle levels in homes without smoking or other strong particle sources are the same as, or lower than, outdoor levels.


Sources: Products used to kill household pests (insecticides, termiticides, and disinfectants). Also, products used on lawns and gardens that drift or are tracked inside the house.

Levels in Homes: Preliminary research shows widespread presence of pesticide residues in homes.


Sources: Pressed wood products (hardwood plywood wall paneling, particle board, fiberboard) and furniture made with these pressed wood products. Urea-formaldehyde foam installation (UFFI). Combustion sources and environmental Tabasco smoke. Durable press drapes, other textiles, and glues

Levels in Homes: Average concentrations in older homes without UFFI are generally well below 0.1 (ppm). In homes with significant amounts of new pressed wood products, levels can be greater than 0.3 ppm.


Sources: Deteriorating, damaged, or disturbed insulation, fireproofing, acoustical materials, and floor tiles.

Levels in Homes: Elevated levels can occur in homes where asbestos-containing materials are damaged or disturbed.

The Inside Story: A Guide to Indoor Air Quality.

Environmental Protection Agency, Consumer Product Safety Commission, Office of Air and Radiation. April 1995.

What are common health effects of indoor air pollution?

Health effects from indoor air pollutants may be experienced soon after exposure or, possibly, years later. Immediate effects may show up after a single exposure or repeated exposures. These include irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue. Such immediate effects are usually short-term and treatable. Sometimes the treatment is simply eliminating the person’s exposure to the source of the pollution, if it can be identified. Symptoms of some diseases, including asthma, hypersensivity pneumonitis, and humidifier fever, may also show up soon after exposure to some indoor air pollutants.


Health Effects: No immediate symptoms. Estimated to contribute to between 7,000 and 30,000 lung cancer deaths each year. Smokers are at higher risk of developing radon-induced lung cancer.


Health Effects: At low concentrations, fatigue in health people and chest pain in people with heart disease. At higher concentrations, impaired vision and coordination; headaches; dizziness; confusion; nausea. Can cause flu-like symptoms that clear up after leaving home. Fatal at very high concentrations.


Health Effects: Eye, nose, and throat irritation; headaches; lung cancer; may contribute to heart disease. Specifically for children, increased risk of lower respiratory tract infections, such as bronchitis and pneumonia, and ear infections; build-up of fluid in the middle ear; increased severity and frequency of asthma episodes; decreased lung function.


Health Effects: Eye, nose, and throat irritation. May cause impaired lung function and increased respiratory infections in young children.


Health Effects: Eye, nose, and throat irritation; shortness of breath; dizziness; lethargy; fever; digestive problems. Can cause asthma; humidifier fever; influenza and other infectious diseases.


Health Effects: Eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans.


Health Effects: Eye, nose, and throat irritation; respiratory infections and bronchitis; lung cancer. (Effects attributable to environmental tobacco smoke are listed elsewhere.)


Health Effects: Eye, nose, and throat irritation; wheezing and coughing; fatigue; skin rash; severe allergic reactions. May cause cancer. May also cause other effects listed under "organic gases."


Health Effects: Irritation to eye, nose, and throat; damage to central nervous system and kidney; increased risk of cancer.


Health Effects: No immediate symptoms, but long-term risk of chest and abdominal cancers and lung diseases. Smokers are at higher risk of developing asbestos-induced lung cancer.

What can I do to my home to reduce indoor air pollution?

Source Control

Usually the most effective way to improve indoor air quality is to eliminate individual sources of pollution or to reduce their emissions. Some sources, like those that contain asbestos, can be sealed or enclosed; others, like gas stoves, can be adjusted to decrease the amount of emissions. In many cases, source control is also a more cost-efficient approach to protecting indoor air quality than increasing ventilation because increasing ventilation can increase energy costs. Specific sources of indoor air pollution in your home are listed later in this section.

Ventilation Improvements

Another approach to lowering the concentrations of indoor air pollutants in your home is to increase the amount of outdoor air coming indoors. Most home heating and cooling systems, including forced air heating systems, do not mechanically bring fresh air into the house. Opening windows and doors, operating window or attic fans, when the weather permits, or running a window air conditioner with the vent control open increases the outdoor ventilation rate. Local bathroom or kitchen fans that exhaust outdoors remove contaminants directly from the room where the fan is located and also increase the outdoor air ventilation rate.


Steps to Reduce Exposure:

  • Test your home for radon--it’s easy and inexpensive

  • Fix you home if your radon level is 4 picoCuries per liter (pCi/L) or higher.

  • Radon levels less than 4 pCi/L still pose a risk, and in many cases may be reduced.

  • If you want more information on radon, contact your state radon office, or call 800-SOS-RADON


Steps to Reduce Exposure:

  • Keep gas appliances properly adjusted.

  • Consider purchasing a vented space heater when replacing an invented one.

  • Use proper fuel in kerosene space heaters.

  • Install and use an exhaust fan vented to outdoors over gas stoves.

  • Open flues when fireplaces are in use.

  • Choose properly sized woodstoves that are certified to meet EPA emission standards. Make certain that doors on all woodstoves fit tightly.

  • Have a trained professional inspect, clean, and tun-up central heating system (furnaces, flues, and chimneys) annually. Repair any leaks promptly.

  • Do not idle the car inside garage.


Steps to Reduce Exposure:

  • Do not smoke in your home or permit others to do so.

  • Do not smoke if children are present, particularly infants and toddlers

  • If smoking indoors cannot be avoided, increase ventilation in the area where smoking takes place. Open windows or use exhaust fans.


Steps to Reduce Exposure:

See steps under carbon monoxide.


Steps to Reduce Exposure:

  • Install and use fans vented to outdoors in kitchens and bathrooms.

  • Vent clothes dryers to outdoors.

  • Clean cool mist and ultrasonic humidifiers in accordance with manufacturer’s instructions and refill with clean water daily.

  • Empty water trays in air conditioners, dehumidifiers, and refrigerators frequently.

  • Clean and dry or remove water-damaged carpets.

  • Use basements as living areas only if they are leak proof and have adequate ventilation. Use dehumidifiers, if necessary, to maintain humidity between 30-50 percent


Steps to Reduce Exposure:

  • Use household products according to manufacture’s directions.

  • Make sure you provide plenty of fresh air when plenty to fresh air when using the products.

  • Throw away unused or little-used containers safely, buy in quantities that you will use soon.

  • Keep out of reach of children and pets.

  • Never mix household car products unless directed on the label.


Steps to Reduce Exposure:

  • Vent all furnaces to outdoors; keep doors to rest of house open when using invented space heaters.

  • Choose properly sized woodstoves, certified to meet EPA emission standards; make certain that doors on all woodstoves fit tightly.

  • Have a trained professional inspect, clean, and tune-up central heating system (furnace, flues, and chimneys) annually. Repair any leaks promptly.

  • Change filters on central heating and cooling systems and air clears according manufacturer’s directions.


Steps to Reduce Exposure:

  • Use "exterior-grade" pressed wood products (lower-emitting because they contain phenol resins, not urea resins).

  • Use air conditioning and dehumidifiers to maintain moderate temperature and reduce humidity levels.

  • Increase ventilation, particularly after bringing new sources of formaldehyde into the home.


Steps to Reduce Exposure:

  • Use strictly according to manufacturer’s directions.

  • Mix or dilute outdoors.

  • Apply only in recommended quantities.

  • Increase ventilation when using indoors. Take plants or pets outdoors when applying pesticides to them.

  • Use nonchemical methods of pest control where possible.

  • If you use a pest control company, select it carefully.

  • Do not store unneeded pesticides inside home; dispose of unwanted containers safely.

  • Store clothes with moth repellents in separately ventilated areas, if possible.

  • Keep indoor spaces clean, dry, and well ventilated to avoid pest and odor problems


Steps to Reduce Exposure:

  • It is best to leave undamaged asbestos material alone if it is not likely to be disturbed.

  • Use trained and qualified contractors for control measures they may disturb asbestos and for cleanup.

  • Follow proper procedures in replacing woodstove door gaskets that may contain asbestos.

This information is taken from "The Inside Story: A Guide to Indoor Air Quality", Environmental Protection Agency, Consumer Product Safety Commission, Office of Air and Radiation. April 1995

For more information...

You can find out more about indoor air pollution by contacting the following organizations:

Environmental Protection Agency

National Center for Environmental Health

National Institute of Environmental Health Sciences (HHS/NIH)

You can also search for more women's environmental health topics at:   "Women’s Health and the Environment: A Federal Inventory of Activities".

All material contained in the FAQs is free of copyright restrictions, and may be copied, reproduced, or duplicated without permission of the Office on Women's Health in the Department of Health and Human Services; citation of the source is appreciated.

Back to FAQ Index


Publication date: 1998

Medical Tools & Articles:

Next articles:

Medical Articles:
CureResearch.comTM Copyright © 2010 Health Grades, Inc. All rights reserved.
Home | Contents | Search | Site Map | Feedback | Contact Us | Terms of Use | Privacy Policy | About Us | Advertise