Is Air Quality a Problem in My Home?
The subject of indoor air pollution or "sick building syndrome" has received a great deal of attention in recent years. Although most of the concern originally focused on the workplace, more people are looking for answers to health and comfort problems occurring in their homes.
The American Industrial Hygiene Association has produced this pamphlet to help homeowners, landlords, and tenants of single-family dwellings recognize and respond to indoor air quality problems. Much of the information presented here applies to apartment buildings as well, but often, only the apartment building owner or manager can remedy the problem. You can prevent or resolve many problems with common sense and a little knowledge of potential air pollutant sources and building systems. This short bulletin cannot address all of the potential problems in the indoor environment. You should also be aware that indoor air quality problems may be due to more than one cause and that health problems may not necessarily be caused by the indoor environment. For these reasons, industrial hygienists and other environmental health scientists will continue to research these complex issues.
What Is Indoor Air Quality?
It is sometimes easier to recognize "poor" indoor air quality than it is to define "good" indoor air quality (IAQ). A few examples that may suggest poor indoor air quality include:
- Stale ("stuffy") air
- Lingering disagreeable odors
- Air that causes eye, nose or throat irritation
- Mold or mildew problems
- Relative humidity levels below 30% or over 60%
- Tobacco smoke
- Excessive dust or allergens, such as animal dander
Good indoor air quality should not cause discomfort or health problems. You can be affected by many factors in the indoor environment to varying degrees. Your health and comfort can also be affected by factors other than air contaminants, such as food, drinking water, poorly designed chairs, air temperature, humidity, and lighting.
Other potential problems are not as obvious as those listed above and can only be detected with scientific testing equipment. These include:
- Naturally-occurring radon gas
- Combustion gases or smoke containing carbon monoxide, nitrogen dioxide and other contaminants from indoor appliances and vehicles
- Pesticides (insecticides, termiticides, herbicides, fungicides, and rodenticides)
- Asbestos from deteriorated insulation
- Lead and other heavy metal dust
Can Poor Indoor Air Quality Cause Serious Health Problems?
Most indoor air quality problems cause discomfort but do not result in health problems. Not everyone reacts the same to IAQ problems. Some people who experience symptoms find that they feel much better soon after leaving the area. Below are some examples of problems that you should be aware of, because they can result in serious illness or death.
Carbon monoxide - Carbon monoxide can build up to hazardous or fatal levels in homes where insufficient outside air is provided to appliances that burn natural gas, propane, fuel oil, or wood. This may include furnaces, space heaters, fireplaces, stoves, water heaters, and clothing dryers. An adequate quantity of outside air should be provided to the furnace area to make up for the air that goes up the exhaust flue. Otherwise, combustion gases containing high amounts of carbon monoxide can "back-draft" down the flue. Combustion appliances should be inspected and cleaned periodically for proper combustion and venting. This is an instance of indoor air problems that can be created by "over tightening" a building for energy saving. Some outside air must be let into your home to replace exhausted air.
Radon gas - Inhalation of radon gas over many years increases the risk of developing lung cancer. Certain soils and rocks give off radon gas. It enters the home through cracks in the foundation, porous concrete blocks, sump openings, unfinished basement floors, and, in some areas, untreated well water. The United States Environmental Protection Agency (EPA) recommends that you test your home to see if radon reduction methods are needed. If a radon reduction device is needed, it should be installed so that it will not cause back-drafting of your furnace or other appliances.
Environmental Tobacco Smoke - Cigarette smoke, which contains carbon monoxide, formaldehyde and thousands of other chemicals, can pose a serious problem in the home environment. Recent studies have shown that exposure to second-hand tobacco smoke may result in inner ear infections, asthma, and lung cancer in non-smokers. The EPA has listed environmental tobacco smoke as a confirmed cancer-causing agent. Parents can greatly improve indoor air quality and reduce discomfort and health risks by preventing indoor smoking.
What You Can Do To Control Indoor Air Pollutants
A quick and cost-effective way to improve the quality of your air is by reducing your use of chemical materials indoors. Some basic rules for maintaining good indoor air quality are:
- Find out what chemicals you have and reduce unnecessary use of chemicals
- Do not bring home chemicals designed for use in the workplace
- Open your windows and/or use fans when using products that give off vapors
- Use household chemicals outside, if possible
- Do not remove paint or varnish indoors with strong solvents or heat guns without adequate ventilation
- Never sand or use a heat gun on lead-based paint indoors
- Do not disturb or remove asbestos-containing materials yourself; hire a contractor licensed for asbestos work
- Store toxic chemicals away from occupied areas
- Use non-chemical methods of pest control whenever possible.
- Properly dispose of any chemicals you do not need
Chemicals in the Home
Inventory all the commercial chemical products or chemically-treated items in your home. You may be surprised to know how many common products contain toxic or irritating chemicals that can affect indoor air. For example, freshly dry-cleaned clothing may give off solvent vapors. Air out your freshly dry-cleaned clothes in an unoccupied room.
Petroleum solvent-based paints release solvent vapors during use and during brush cleaning. Use water-based paints whenever possible, but make sure they do not contain mercury. Paint stripping chemicals can contain methylene chloride, which is a suspected cancer-causing agent.
Never store gasoline in the home. It is highly flammable and may release benzene (which may cause cancer) and other hydrocarbon vapors. Never use gasoline as a cleaning solvent!
Pesticides should only be used when absolutely necessary. Even moth balls give off potentially hazardous substances in small amounts. Pesticides should be stored in the garage or away from inhabited areas. Hire a licensed pesticide applicator if you have a major pest problem. Check the pest control company's references, ask to see Material Safety Data Sheets for the products it uses and review the company's procedures to ensure that they address your concerns.
Be careful when disposing of unneeded chemicals. Many localities have household hazardous material disposal sites to drop off old paints, solvents, pesticides, and other chemicals.
How Can Building Materials and Furnishings Affect Indoor Air?
A number of materials used in constructing, furnishing, and insulating a home contribute small, but sometimes noticeable amounts of dusts or irritating vapors.
Formaldehyde
Plywood, particle-board, and other pressed wood products are often held together with formaldehyde-based resins. Formaldehyde can cause eye, nose and throat irritation, and several federal agencies list it as a cancer-causing agent. Some people can become sensitized to formaldehyde and experience severe skin or respiratory symptoms. Federal standards require formaldehyde emission testing and labeling. Look for this labeling when you buy wood products.
Insulation
Insulation materials can affect indoor air quality. Urea-Formaldehyde Foam Insulation (UFFI) was used in the walls of many homes in the 1970s. UFFI is very rarely used today. This type of insulation resulted in significant levels of formaldehyde in some homes. Formaldehyde vapors from this source decrease with time, but sensitized people may react to low levels or decomposed UFFI dust. Exposed fiberglass insulation inside air ducts can release irritating fibers if it breaks down with age or water damage. Try to find fiberglass insulation with a plastic outer lining. Any kind of insulation can be a problem if it gets wet, since it can harbor molds and mildew.
Carpet Furnishings
Old carpets and some fabrics can harbor molds, dust mites (microscopic insects that may cause allergic reactions), allergenic animal hairs or dusts, and lead-containing dust. Because the air filters on most household vacuum cleaners are not very efficient, microscopic allergens can get into the air. If you have a respiratory illness or severe allergies you should consider installing a central vacuum system that discharges the filtered air outside the building; or try using a portable vacuum cleaner equipped with high efficiency particulate air (HEPA) filters.
New carpets, carpet backings and adhesives may release volatile organic compounds and other irritating vapors. Here are a few simple suggestions for preserving good indoor air quality:
- Contact the manufacturer and ask for any available health testing information
- Have the dealer unroll and air out the carpet before installation
- Try using nails instead of adhesives, if possible
- Provide plenty of fresh air to the space during installation and for a few days after installation
What About Mold and Mildew?
Many people are allergic to molds, mildew, and other fungal spores. Some molds cause disease or release toxic substances. Molds and mildew may be in areas of your home with high humidity such as areas with improper drainage, porous foundation materials and improperly maintained humidifiers, dehumidifiers, or air conditioners. A single flooding event can create a mold or mildew problem.
To avoid these problems, do not allow water to form pools or wet spots inside or immediately outside your home. Thoroughly clean and disinfect or remove surfaces where molds have grown in the past. Humidifiers with a water reservoir can cause mold or bacterial contamination of indoor air, and should be cleaned thoroughly at least once a week. Empty and clean the water collection pans of refrigerators, dehumidifiers, and air conditioners frequently.
Testing for airborne fungi is generally not necessary and is expensive. It is generally more cost-effective to remove all visible mold growth and disinfect or dispose of the material. Reduce the moisture that leads to mold growth by sealing and patching walls and floors either at the source and/or by using a dehumidifier.
If your home suffers flood damage, clean and disinfect water-damaged furnishings and construction materials as soon as possible. Porous surfaces, such as carpets or fabrics, may not be as easy to clean as smooth or painted surfaces, such as linoleum. Discard anything you cannot clean and dry, since even dry spores can continue to cause allergies. Contact the IAQ Clearinghouse for EPA flood clean-up guidelines.
What if You Cannot Control the Source?
Ventilation and air-cleaning devices can reduce exposure to air pollutants that cannot be eliminated by source control:
- To reduce carbon monoxide build-up and improve efficiency, provide outside air to the furnace
- For new construction, consider air-to-air heat exchangers to save energy while bringing in more outside air
- Use exhaust fans to vent kitchen and bathroom pollutants to the outside
- Use higher efficiency furnace air filters and change filters frequently
- Consult EPA publications and choose air-cleaning devices carefully
A wide variety of "air cleaners" are now on the market. Before investing in such a device, carefully evaluate the manufacturer's claims and the limitations of the device. Many air cleaners work well controlling dust particles but do not control odors or vapors. Pay particular attention to the frequency and cost of replacement filters and ease of cleaning. A poorly-maintained air cleaner can frequently make the air quality worse rather than better.
Testing Your Indoor Air Quality
No single air testing method is available to figure out the total quality of your home air. Air testing is often not worthwhile unless you know exactly what to test for. Discomfort or unusual odors are the best judge of indoor air quality in homes. Some pollutants, such as radon and carbon monoxide, are odorless, colorless, and tasteless and can only be evaluated by testing. Carbon monoxide and radon test kits may be available through your local American Lung Association or your local hardware store.
If you have concerns about combustion product back-drafting, some contractors can help you test whether back-drafting is likely in your home. Carbon monoxide detecting alarms are also available for continuous testing.
Other air monitoring devices are available for formaldehyde and specific organic compounds. Use of some sampling devices requires scientific training and analysis by a qualified laboratory. Your local or state department of health can refer you to local sources for sampling device purchase and analysis.
After you have exhausted all other avenues without success, contact a reputable contractor or a professional industrial hygiene consultant. Make sure to check references and indoor air quality experience.
Beware of Scams
The field of indoor air quality investigation and remediation is relatively new. As a result, many opportunists have emerged to profit from your lack of knowledge and your desire for a healthy environment. An example is the ozone generator, which some companies promote as a "cure" for indoor formaldehyde and odors. Although the manufacturers claim that the units neutralize odors and chemical pollutants, they may produce ozone at levels above what is considered safe.