Basic approaches to control indoor air pollution include source control, source isolation, increased ventilation, dehumidification, and the use of filters (see the table). Possible sources of contamination are eliminated in a source-control strategy. Examples include banning smoking in public buildings, using carefully selected building materials to avoid the emission of toxic or irritating substances, and limiting the use of fibrous materials. Source-isolation strategy is used in situations where a source cannot be completely eliminated. For instance, copy machine areas, food service stations, and bathrooms are often separately vented outside buildings to avoid the recirculation of return air. Existing sources of pollution such as leaded paint and asbestos insulation may either be removed or encapsulated. Increased ventilation and filtration are traditional approaches to ensuring good indoor air quality. Dehumidification helps in the reduction of microbial growth. Low humidity should be maintained inside a house to limit the growth of such bacteria.
Devices based on the principles of absorption and adsorption are finding applications in controlling indoor air pollutants and moisture. Solid and liquid desiccants have been found effective in removing moisture and a wide range of pollutants. Silica gel, activated alumina, and activated carbon are also used to adsorb gases and vapors. Spider plants have been found to absorb some volatile organic compounds (VOCs) from indoor air.
The number of lawsuits filed in the area of indoor air pollution dramatically increased between 1970 and 2001. The U.S. Environmental Protection Agency's Building Assessment Survey Evaluation found that in the worst buildings of the first study group, approximately 30 to 40 percent of occupants experienced headaches, unusual fatigue or drowsiness, and dry, itching, or otherwise irritated eyes at least once a week. In the best buildings of the same study group, 6 percent of occupants experienced unusual fatigue or drowsiness. Under these circumstances, the possibility of complaints filed in relationship to indoor air quality will not become remote in coming years.