Indoor air quality (IAQ) is the air quality within and around buildings and structures. IAQ is known to affect the health, comfort, and well-being of building occupants. Poor indoor air quality has been linked to sick building syndrome, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: Secondhand tobacco smoke, air pollutants from indoor combustion, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, asbestos fibers, carbon dioxide, ozone and particulates. Source control, filtration, and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality in most buildings.
Indoor air is typically several times more polluted than the air outside, especially after recent painting or where indoor fires are used. In some less developed communities, indoor smoke from cooking fires is a major cause of disease and death, especially among children.
Volatile Organic Compounds (VOCs)[edit | edit source]
Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors. VOCs are emitted by a wide array of products numbering in the thousands. Examples include: paints and lacquers; paint strippers; cleaning supplies; pesticides; building materials and furnishings; office equipment such as copiers and printers, correction fluids, and carbonless copy paper; and graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.
Organic chemicals are widely used as ingredients in household products. Paints, varnishes, and waxes all contain organic solvents, as do many cleaning, disinfecting, cosmetic, degreasing, and hobby products. Fuels are also made up of organic chemicals. All of these products can release organic compounds while you are using them, and to some degree, when they are stored.
The Environmental Protection Agency's Office of Research and Development's "Total Exposure Assessment Methodology (TEAM) Study" (Volumes I through IV, completed in 1985) found levels of about a dozen common organic pollutants to be two to five times higher inside homes than outside, regardless of whether the homes were located in rural or highly industrial areas. TEAM studies indicated that while people are using products containing organic chemicals, they can expose themselves and others to very high pollutant levels, and elevated concentrations can persist in the air long after the activity is completed.
Sources[edit | edit source]
Household products are sources of indoor air pollution, including paints, paint strippers, and other solvents; wood preservatives; aerosol sprays; cleansers and disinfectants; moth repellents and air fresheners; stored fuels and automotive products; hobby supplies; and dry-cleaned clothing.
Health Effects[edit | edit source]
Health effects of indoor air pollution include eye, nose, and throat irritation; headaches, loss of coordination, nausea; and damage to the liver, kidney, and central nervous system. Some organic chemicals can cause cancer in animals; some are suspected or known to cause cancer in humans. Key signs or symptoms associated with exposure to VOCs include: conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, emesis, epistaxis, fatigue, and dizziness.
The ability of organic chemicals to cause health effects varies greatly from those that are highly toxic to those with no known health effect. As with other pollutants, the extent and nature of the health effect will depend on many factors, including level of exposure and length of time exposed. Eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment are among the immediate symptoms that some people have experienced after exposure to some organic chemicals. At present, not much is known about what health effects occur from the levels of organic chemicals usually found in homes.
For more information about health effects from indoor air pollution, read the following resources:
- Search the Environmental Protection Agency's Integrated Risk Information System (IRIS) (a compilation of electronic reports on specific substances found in the environment and their potential to cause human health effects)
- Drinking water regulations - Contaminant Specific Fact Sheets: Volatile Organic Chemicals
- Review information on VOCs in water sources developed by the U.S. Geology Survey's National Water-Quality Assessment (NAWQA) Program and their Toxic Substances Hydrology Program: Toxic Program Research on VOCs
Indoor Air Pollution Levels in Homes[edit | edit source]
Studies have found that indoor air pollution levels of several organic chemicals average two to five times higher indoors than outdoors. During and for several hours immediately after certain activities, such as paint stripping, levels may be 1,000 times higher than outdoor levels.
Steps to Reduce Exposure[edit | edit source]
Plants that remove indoor air pollutants[edit | edit source]
NASA did a major research project into plants that improve air quality for humans, with a view to eventually being able to use plants to recycle air for astronauts on the space shuttle. The best plants they found at reducing carbon dioxide, creating oxygen, and removing toxins like benzene and formaldehyde were:
- Peace lily (Spathiphyllum spp.)
- Money plant (Epipremnum Aureum)
- Snake plant (Sansevieria Trifasciata)
- Areca palm (Chrysalidocarpus Lutescens)
From NASA's website - "In 1973, NASA scientists identified 107 volatile organic compounds (VOCs) in the air inside the Skylab Space Station. Synthetic materials, like those used to construct Skylab, give off low levels of chemicals. This effect, known as off-gassing, spreads the VOCs, such as formaldehyde, benzene, and trichloroethylene, all known irritants and potential carcinogens. When these chemicals are trapped without circulation, as was the case with the Skylab, the inhabitants may become ill, as the air they breathe is not given the natural scrubbing by Earth's complex ecosystem.... Once the plants were introduced to the environment, analysis of the air quality indicated that most of the VOCs had been removed, and the symptoms disappeared."
General Steps to Reduce Exposure
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- Increase ventilation when using products that emit VOCs.
- Meet or exceed any label precautions.
- Do not store opened containers of unused paints and similar materials within a school.
- Formaldehyde, one of the best known VOCs, is one of the few indoor air pollutants that can be readily measured.
- Identify, and if possible, remove the source. If it is not possible to remove the source, reduce exposure by using a sealant on all exposed surfaces of paneling and other furnishings.
- Use integrated pest management techniques to reduce the need for pesticides.
- Open windows to allow through ventilation. If you cannot achieve adequate ventilation then do not use spray paints or paints that contain a base of volatile compounds.
- When painting, use natural paints
- Take care with household products that contain volatile compounds:
- Choose safer products where possible (e.g. see green cleaning)
- Use household products according to manufacturers' directions.
- Make sure you provide plenty of fresh air when using these 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 care products unless directed on the label.
Specific Steps to Reduce Exposure
[edit | edit source]
Follow label instructions carefully.[edit | edit source]
Potentially hazardous products often have warnings aimed at reducing exposure of the user. For example, if a label says to use the product in a well-ventilated area, go outdoors to use it. Otherwise, open up windows to provide the maximum amount of outdoor air possible. Note that having a fan in the room does not improve ventilation in a room unless it is placed so that it can bring fresh outdoor air into the room.
Throw away partially full containers of old or unused chemicals safely.[edit | edit source]
Buy limited quantities[edit | edit source]
If you use products only occasionally or seasonally, such as paints, paint strippers, and kerosene for space heaters or gasoline for lawn mowers, buy only as much as you will use right away.
Keep exposure to emissions from products containing methylene chloride to a minimum[edit | edit source]
Consumer products that contain methylene chloride include paint strippers, adhesive removers, and aerosol spray paints. Methylene chloride is known to cause cancer in animals. Also, methylene chloride is converted to carbon monoxide in the body and can cause symptoms associated with exposure to carbon monoxide. Carefully read the labels containing health hazard information and cautions on the proper use of these products. Use products that contain methylene chloride outdoors when possible; use indoors only if the area is well ventilated.
Keep exposure to benzene to a minimum[edit | edit source]
Benzene is a known human carcinogen. The main indoor sources of this chemical are environmental tobacco smoke, stored fuels and paint supplies, and automobile emissions in attached garages. Actions that will reduce benzene exposure include eliminating smoking within the home, providing for maximum ventilation during painting, and discarding paint supplies and special fuels that will not be used immediately.
Keep exposure to perchloroethylene emissions from newly dry-cleaned materials to a minimum[edit | edit source]
Perchloroethylene is the chemical most widely used in dry cleaning. In laboratory studies, it has been shown to cause cancer in animals. Recent studies indicate that people breathe low levels of this chemical both in homes where dry-cleaned goods are stored and as they wear dry-cleaned clothing. Dry cleaners recapture the perchloroethylene during the dry cleaning process so they can save money by reusing it, and they remove more of the chemical during the pressing and finishing processes. Some dry cleaners, however, do not remove as much perchloroethylene as possible all of the time. Taking steps to minimize your exposure to this chemical is prudent. If dry-cleaned goods have a strong chemical odor when you pick them up, do not accept them until they have been properly dried. If goods with a chemical odor are returned to you on subsequent visits, try a different dry cleaner.
Standards or Guidelines[edit | edit source]
No standards have been set for VOCs in nonindustrial settings. The Occupational Safety and Health Administration (OSHA) regulates formaldehyde, a specific VOC, as a carcinogen. OSHA has adopted a Permissible Exposure Level (PEL) of 0.75 ppm, and an action level of 0.5 ppm. U.S. Housing and Urban Development (HUD) has established a level of 0.4 ppm for mobile homes. Based upon current information, it is advisable to mitigate formaldehyde that is present at levels higher than 0.1 ppm.
References[edit | edit source]
Additional Resources[edit | edit source]
Indoor Air Fact Sheet No. 4 (revised) - Sick Building Syndrome
Explains the term "sick building syndrome" (SBS) and "building related illness" (BRI). Discusses causes of sick building syndrome, describes building investigation procedures, and provides general solutions for resolving the syndrome.
- HTML Version
- [EPA 402-F-94-004, April 1991]
Indoor Air Pollution: An Introduction for Health Professionals
Assists health professionals (especially primary care physicians) in diagnosis of patient symptoms that could be related to an indoor air pollution problem. Addresses the health problems that may be caused by contaminants encountered daily in the home and office. Organized according to pollutant or pollutant groups (such as environmental tobacco smoke, VOCs, biological pollutants, and sick building syndrome), this booklet lists key signs and symptoms from exposure to these pollutants, provides a diagnostic checklist and quick reference summary, and includes suggestions for remedial action. Also includes references for information contained in each section. This booklet was coauthored with the American Lung Association, the American Medical Association, and the U.S. Consumer Product Safety Commission.
- HTML Version
- [EPA 402-R-94-007, 1994]
See also[edit | edit source]
- Green cleaning
- Natural paints
- VOCs in plywood
- VOCs in fiberglass insulation
- Carbon monoxide (CO)
- Pressed wood products
- Nitrogen dioxide (NO2)
- Air pollution
- Improved cook stoves
- Organic chemicals
- Environmental Protection Agency
- Methylene cholride
- Dry cleaning
- Occupational Safety and Health Administration
- Housing and Urban Development
- American Lung Association
- American Medical Association
- U.S. Consumer Product Safety Commission
[edit | edit source]
- GREENGUARD Environmental Institute - an Atlanta-based, US nonprofit organization that works to improve the quality of the air inside homes, offices, and classrooms.
- "The Inside Story: A Guide to Indoor Air Quality" and "Care for Your Air" - Information on Pollutants and Sources of Indoor Air Pollution