An Overview of Indoor Air Quality
In the last several years, a growing body of scientific evidence has indicated that the air within homes and other buildings can be more seriously polluted than the outdoor air in even the largest and most industrialized cities. Other research indicates that people spend approximately 90% of their time indoors. Thus, for many people, the risks to health may be greater due to exposure to air pollution INDOORS than OUTDOORS.
In addition, people who may be exposed to indoor air pollutants for the longest periods of time are often those most susceptible to the effects of indoor air pollution. Such groups include the young, the elderly and the chronically ill, especially those suffering from respiratory or cardiovascular disease.
While pollutant levels from individual sources may not pose a significant health risk by themselves, most homes have more than one source that contributes to indoor air pollution. There can be a serious risk from the cumulative effects of these sources. This also can be said about commercial office buildings, hotels, motels, multi-dwelling residences, in essence all enclosed habitats.
Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems in buildings. Inadequate ventilation can increase indoor pollutant levels by NOT bringing in enough outdoor air to dilute emissions from indoor sources AND by NOT carrying indoor air pollutants out of the building. Room temperature and humidity levels can also increase concentrations of some pollutants such as mold, mildew, bacteria and dust mites.
Excessive humidity levels can cause significant damage to a house.
Condensation, for example, on a cold surface (windows and outside walls) causes deterioration of paint, wallpaper, rotting of wood, and potential mold growth.
Areas of the house that can have continuous water and humidity damage include crawl spaces, attics, basements, kitchens and bathrooms.
Besides being a major contributor to mold growth, high humidity also increases problems with bacteria, viruses, mites, VOCs and ozone.
There are many sources of indoor air pollution in any home. These include combustion sources such as oil, gas, kerosene, coal, wood and tobacco products; building materials and furnishings as diverse as deteriorated asbestos-containing insulation, wet or damp carpet and cabinetry or furniture made of certain pressured wood products; products for household cleaning and maintenance, personal care, or hobbies; central heating and cooling systems and humidification devices; and outdoor sources such as radon, pesticides and outdoor pollution.
The relative importance of any single source depends on how much of a given pollutant it emits and how hazardous those emissions are. In some cases, factors such as how old the source is and whether it is properly maintained are significant. For example, an improperly adjusted gas stove can emit significantly more carbon monoxide than one that is properly adjusted.
Some sources, such as building materials, furnishings and household products like air fresheners, release pollutants more or less continuously. Other sources, related to activities carried out in the home, release pollutants intermittently. These include smoking, the use of non-vented or malfunctioning stoves, furnaces or space heaters, the use of solvents in cleaning and hobby activities, the use of paint strippers in redecorating activities, and the use of cleaning products and pesticides in housekeeping. High pollutants concentrations can remain in the air for a long periods after some of these activities.
We must not overlook the building's occupants as a problem source. This includes not only the people but also pets and plants.
Each one of these occupants can release heat and moisture and emit and absorb a wide variety of pollutants. The moving occupants tend to deposit pollutants throughout the building.
People exercise the largest control over humidity and moisture. They operate the heating and cooling systems. They cook wash and bathe and even undertake other activities that can cause excessive moisture (power washing the house, leaving windows open during storms, cutting back on heating and/or cooling systems during extended absences.
Health effects from indoor air pollutants may be experienced soon after exposure or, possibly, years later.
Immediate effects may show up after a single exposure or repeated exposures. These include irritation of the eyes, nose and throat, headaches, dizziness and fatigue. Such effects are usually short-term and treatable. Sometimes the treatment is simply eliminating the person's exposure to the source of the pollution, if it can be identified. Symptoms of some diseases, including asthma, hypersensitivity pneumonitis and humidifier fever, may also show up soon after exposure to some indoor air pollutants.
The likelihood of immediate reaction to indoor air pollutants depends on several factors. Age and preexisting medical conditions are two important influences. In other cases, whether a person reacts to a pollutant depends on individual sensitivity, which varies tremendously from person to person. Some people can become sensitized to biological pollutants after repeated exposures, and it appears that some people can become sensitized to chemical pollutants as well.
Certain immediate effects are similar to those from colds or other viral diseases, so it is often difficult to determine if the symptoms are a result of exposure to indoor air pollution. for this reason, it is important to pay attention to the time and place the symptoms occur. If the symptoms fade or go away when the person is away from the home and returns when the person returns, an effort should be made to identify indoor air sources that may be possible causes. Some effects may be made worse by an inadequate supply of outdoor air or from, heating, cooling or humidity conditions prevalent in the home.
Other health effects may show up either years after exposure has occurred or only after long or repeated periods of exposure. These effects, which include some respiratory diseases, heart disease and cancer, can be severely debilitating or fatal. It is prudent to try to improve the indoor air quality in your home EVEN if symptoms are not noticeable..