Indoor Air Quality in Home Environments

Sources of Indoor Air Pollutants

Indoor air pollutants have increased over the part few decades for variety of reasons. Contributing to indoor air quality issues in homes are construction of more tightly sealed buildings, reduced ventilation rates to save energy, the use of synthetic building materials and furnishings, and increased use of chemical products such as pesticides, housekeeping supplies, and personal care products. The four basic factors affecting indoor air quality (IAQ) are indoor air pollutant sources; the heating, ventilation, and air-conditioning (HVAC) system; pollutant pathways; and occupants.

Typical sources of indoor air pollutants and conditions that can have an impact on IAQ in homes:

• Moisture and Biologicals
• Combustion Products, including Carbon Monoxide
• Environmental Tobacco Smoke
• Formaldehyde
• Radon
• Household Products and Furnishings (VOCs)
• Particulates
• Lead-Based Paint
• Asbestos
• A note about Asthma

See also:
US EPA: Indoor Air Quality (IAQ) in Homes/Residences

Moisture and Biologicals: Moisture problems in homes can result in the growth or amplification of biological and microbial organisms like mold, mildew, dust mites and pet dander. Exposure to these organisms can increase the risk of allergic illness, trigger asthma, cause respiratory infections, or have other health effects. Common sources of moisture include high indoor humidity, plumbing leaks, and water leaks. Poorly maintained heating, ventilation and air-conditioning systems can also contribute to moisture problems. To remedy the problem, the source of excess moisture must be found and fixed, and contaminated materials must be removed and discarded if they can not be thoroughly cleaned.

For more detailed information, see:
NC DHHS/OEEB: Mold and Human Health
US EPA: Biological Pollutants in Your Home
US EPA: A Brief Guide to Mold, Moisture, and Your Home

Combustion Products, including Carbon Monoxide: Adverse health effects from combustion products range from mild effects to death. Carbon monoxide, a deadly gas, kills over 200 people year in the United States. Other pollutants, such as nitrogen oxides, can cause breathing problems, particularly in sensitive individuals, and can trigger asthma attacks. Sources of combustion products include unvented fossil-fuel (oil, kerosene) heaters, unvented gas stoves and ovens, and back-drafting and malfunctioning furnaces and water heaters. During power outages, the indoor use of charcoal or gas grills or of gas-powered generators can cause serious carbon monoxide poisoning and possible death to people in the home. To ensure that combustion pollutants do not create IAQ problems, take the following steps:

1. All potential sources should be vented to the outside of the building.
2. Make sure all systems are regularly maintained and inspected.
3. Install carbon monoxide monitors in homes where there are fossil-fuel burning appliances.
4. NEVER USE a charcoal or gas grill indoors for cooking or heating.
5. NEVER USE a gasoline-powered generator indoors. Gas-powered generators MUST be used outdoors, in a well-ventilated area away from windows, doors and home air-intakes.

The following web sites also contain details on combustion products/pollutants:
US EPA: Carbon Monoxide (CO)
US EPA: Protect Your Family and Yourself From Carbon Monoxide Poisoning
New York State Department of Health: Supplemental Space Heaters

Environmental Tobacco Smoke: Secondhand smoke, or environmental tobacco smoke (ETS), can cause significant IAQ problems in homes and other buildings. ETS is a mixture of the smoke given off by the burning end of a cigarette, pipe or cigar, and the smoke that is exhaled from the lungs of the smoker. ETS contains more than 4,000 chemical compounds, approximately 40 of which are carcinogens or suspected carcinogens. Secondhand smoke has been classified by the U.S. Environmental Protection Agency (EPA) as a known cause of lung cancer in humans (Group A carcinogen). Children who breathe ETS are more likely to suffer from ear infections, pneumonia, bronchitis, and other lung diseases. ETS can increase the risk of asthma attacks in persons with asthma. For all these reasons, smoking should not be allowed in homes where there are children.

See also:
NC DHHS: Tobacco Prevention and Control Branch
US EPA: Secondhand Smoke/Environmental Tobacco Smoke/Smoke-free Homes

Formaldehyde: Sources of formaldehyde include durable-press drapes and other textiles, particleboard products such as cabinets and furniture, tobacco smoke and adhesives. Formaldehyde is an irritant to the eyes, nose and throat, and can cause tearing of the eyes, coughing and bronchial spasms. Formaldehyde is also a suspected human carcinogen. Careful selection of products and increased ventilation can help reduce health effects.

For more information, see:
US EPA: Formaldehyde
US EPA: An Update on Formaldehyde

Radon: Radon is a naturally occurring, invisible, odorless gas that comes from natural deposits of uranium in soil, rock, and water. Radon is harmlessly dispersed in outdoor air, but when trapped in buildings, it can be harmful, especially at elevated levels. There are no immediate symptoms from radon exposure. However, long-term radon exposure has been linked to between 7,000 and 30,000 lung cancer deaths each year. Lung cancers usually occur 5 - 25 years after exposure. In North Carolina, piedmont and mountain counties are estimated to have the greatest proportion of homes with elevated levels of radon.

For information on testing your home for radon and protecting your family from its effects:
NCSU / NC DENR: Division of Radiation Protection
US EPA: Consumer's Guide to Radon Reduction

Household Products and Furnishings: Volatile organic compounds (VOCs) come from paints, solvents, pesticides, air fresheners, hobby supplies, dry-cleaned clothing, aerosol sprays, adhesives and fabric additives and wood treated with arsenic (CCA). Some of these VOCs can cause eye, nose and throat irritation; headaches; loss of coordination; nausea; or damage to the liver, kidneys, and central nervous system.

See also:
US EPA: Pesticides
US EPA: Organic Gases (Volatile Organic Compounds - VOCs)
NC DHHS: What You Should Know About CCA-Treated Wood

Particulates: Fireplaces, wood stoves kerosene heaters and unvented gas space heaters can produce air-borne particles (particulates). Dust and pollen are also considered particulates. Health effects from exposure to tiny particles that can be breathed into the lungs depend on the types and concentrations of the particles, the frequency and duration of exposure, and individual sensitivity. Health effects can range from irritation of the eyes and/or respiratory tissues to more serious effects, such as cancer and decreased lung function. Biological particles, such as animal and insect allergens, viruses, bacteria, and molds, can cause allergic reactions or infectious diseases.

See also:
US EPA: Residential Cleaning Devices - A Summary of Available Information
US EPA: Respirable Particles/Combustion Products

Lead-Based Paint: If your home was built prior to 1978, lead-based paint may have been used in your home. If you have concerns about lead-based paint, please refer to the NC DHHS web site "Lead Poisoning in North Carolina."

Asbestos: Some building products used in homes may contain asbestos. If you have concerns about asbestos in your home, refer to the following NC DHHS "Asbestos in North Carolina" web site for more information.

Asthma: A recent survey of more than 100,000 North Carolina middle school students found that 10 percent of those students had diagnosed asthma, while 17 percent more students had asthma symptoms that had not been diagnosed. There is ample and clear evidence that environmental exposure can make asthma worse, and mounting evidence that many of the same exposures play a role in causing the disease. Numerous epidemiological studies have shown that, when asthmatics are exposed to building contaminants like dust mites, cockroach and mold antigens, combustion gases, and tobacco smoke, those individuals have more frequent and more serious asthma attacks. Minimizing these exposures in the indoor environment can have a profound effect on improving the respiratory health of asthma patients.

See also:
US EPA: Clear Your Home of Asthma Triggers
US EPA: Indoor Environmental Asthma Triggers
US EPA: A Brief Guide to Mold, Moisture, and Your Home
American Lung Association of North Carolina

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