Indoor Air Quality

An ozone warning has been issued and you know you should stay inside. So you cancel the outdoor run you had scheduled and work out on your indoor stationery bike instead. You made the right decision by reducing your exposure to outdoor air pollution, but is the indoor environment any better? It may be hard to believe but Americans spend 90% of their time in indoor environments, including homes, schools, and offices. Indoors they may be exposed to pollutant concentrations that can be to 2-5 times and sometimes even 100 times higher than outdoor levels.

Many pollutants accumulate indoors

Since the energy crisis of the 1970's, construction methods have changed to make structures increasingly airtight. The reduction of air flow between interiors of buildings and the outside environment can result in the accumulation of pollutants from a variety of indoor sources. Paints, laminated wood products, vinyl flooring, carpet padding, adhesives, upholstered furniture, and draperies give off organic chemical fumes. Combustion sources such as stoves, fireplaces, and water heaters create higher levels of nitrogen dioxide indoors. Cigarette smoke, also called environmental tobacco smoke (ETS), is the most studied indoor air pollutant and is a known carcinogen. Many of the consumer products we use in our homes also add to indoor pollution levels. Carelessly or excessively using everyday household cleaning products can cause harmful levels of toxins to build up indoors. Most commercial pest control products are laced with toxins that kill not only pests, but have a detrimental effect on human health as well. Even the chemical emitted from newly dry cleaned clothes has been shown to cause cancer in animals.

Public buildings differ from homes

In addition to many of the indoor pollutants found in homes, office buildings have their own unique indoor air pollution sources. Heating, ventilation and air conditioning systems (HVAC) are different in commercial buildings because they circulate a mixture of outdoor and indoor air throughout the building. Office paper contributes to poor indoor air quality (IAQ) both through chemicals used to treat paper and the inks and toners used in copy machines and laser printers. Chemicals from printing, photo processing, and dry cleaning services conducted in an office building can be circulated throughout the entire building and affect all of the occupants inside.

Schools have multiple indoor air pollution sources

Schools have the same sources of indoor pollutants as homes and office buildings as well as a few of their own. Arts and crafts supplies are widely used and schools often have science and computer labs. Some have vocational areas for welding, cosmetology, and automotive shops. Each of these sources contributes a different type of indoor pollution from the solvents, adhesives, and chemicals used for each task. Schools also have to deal with more difficult challenges such as older buildings, improper maintenance, and inadequate ventilation systems. Temporary buildings have their own set of IAQ problems related to the formaldehyde used in construction materials.

What you can do to improve indoor air quality

Although indoor air pollutants are numerous, there are two simple steps you can take to improve indoor air quality. The first is to control sources by eliminating the source itself, such as mothballs, or by reducing source emissions. The second step is to increase outdoor air ventilation by opening windows, doors and vents on good outdoor air quality days. The EPA has developed an indoor air quality program for schools called Tools for Schools that uses a team of school staff to survey the school, identify problem areas, and recommend improvements. Many of the solutions involve little to no cost and can be performed without outside assistance. For more on EPA's Tools for Schools and healthy school environments see http://cfpub.epa.gov/schools/index.cfm.