Indoor Air quality has become a topic of concern. “Indoor air quality” refers to the quality of the air in a home, school, office, or other building environment. The potential impact of indoor air quality on human health nationally can be noteworthy for several reasons:
Americans, on average, spend approximately 90 percent of their time indoors,1 where the concentrations of some pollutants are often 2 to 5 times higher than typical outdoor concentrations.
People who are often most susceptible to the adverse effects of pollution (e.g., the very young, older adults, people with cardiovascular or respiratory disease) tend to spend even more time indoors.
Indoor concentrations of some pollutants have increased in recent decades due to such factors as energy-efficient building construction (when it lacks sufficient mechanical ventilation to ensure adequate air exchange) and increased use of synthetic building materials, furnishings, personal care products, pesticides, and household cleaners.
Outdoor climate and weather conditions combined with occupant behavior can also affect indoor air quality. Weather conditions influence whether building occupants keep windows open or closed and whether they operate air conditioners, humidifiers, or heaters, all of which can affect indoor air quality. Certain climatic conditions can increase the potential for indoor moisture and mold growth if not controlled by adequate ventilation or air conditioning.
The link between some common indoor air pollutants (e.g., radon, particle pollution, carbon monoxide, Legionella bacterium) and health effects is very well established.
Radon is a known human carcinogen and is the second leading cause of lung cancer.
Carbon monoxide is toxic, and short-term exposure to elevated carbon monoxide levels in indoor settings can be lethal.
Episodes of Legionnaires' disease, a form of pneumonia caused by exposure to the Legionella bacterium, have been associated with buildings with poorly maintained air conditioning or heating systems.
Numerous indoor air pollutants—dust mites, mold, pet dander, environmental tobacco smoke, cockroach allergens, particulate matter, and others—are “asthma triggers,” meaning that some asthmatics might experience asthma attacks following exposure.
While adverse health effects have been attributed to some specific pollutants, the scientific understanding of some indoor air quality issues continues to evolve.
One example is “sick building syndrome,” which occurs when building occupants experience similar symptoms after entering a particular building, with symptoms diminishing or disappearing after they leave the building. These symptoms are increasingly being attributed to a variety of building indoor air attributes. Researchers also have been investigating the relationship between indoor air quality and important issues not traditionally thought of as related to health, such as student performance in the classroom and productivity in occupational settings. Another research area that is evolving is “green building” design, construction, operation, and maintenance that achieves energy efficiency and enhances indoor air quality.