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Indoor Air Pollutants

Indoor Air Pollutants, Their Health Effects and Their Sources

It maybe to your advantage to read our section “Outdoor Air Pollutants, Their Health Effects and Their Sources” before reading the information below in order to build a working knowledge of pollution emissions. 

Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems. Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute indoor emissions and by not carrying indoor air pollutants out of the indoor environment. High temperature and humidity levels can also increase concentrations of some pollutants. 

The relative importance of any single source depends on how much of a given pollutant is emitted 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 indoor space, release pollutants intermittently. These include smoking; the use of unvented or malfunctioning stoves, furnaces, or space heaters; the use of solvents in cleaning, and craft activities; the use of paint strippers in redecorating activities; and the use of cleaning products and pesticides in housekeeping. High pollutant concentrations can remain in the air for long periods after some of these activities.


  • Additional Typical Sources of Indoor Air Pollutants

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    Outdoor Sources

    Building Equipment

    Components/Furnishings

    Other Potential Indoor Sources

    Polluted Outdoor Air

    • Pollen, dust, mold spores
    • Industrial emissions
    • Vehicle and non-road engine emissions (cars, buses, trucks, lawn and garden equipment

    Nearby Sources

    • Loading docks
    • Odors from dumpsters
    • Unsanitary debris or building exhausts near outdoor air intakes

    HVAC Equipment

    • Mold growth in drip pans, ductwork, coils, and humidifiers
    • Improper venting of combustion products
    • Dust or debris in ductwork

    Non-HVAC Equipment

    • Emissions from office equipment (volatile organic compounds (VOCs), ozone)
    • Emissions from shop, lab, and cleaning equipment
    • Asbestos-containing insulation

    Components

    • Mold growth on or in soiled or water-damaged materials
    • Dry drain traps that allow the passage of sewer gas
    • Materials containing VOCs, inorganic compounds, or damaged asbestos
    • Materials that produce particles (dust)

    Furnishings

    • Emissions from new furnishings and floorings (VOCs)
    • Mold growth on or in soiled or water-damaged furnishings
    • Science laboratory supplies
    • Vocational art supplies
    • Copy/print areas
    • Food prep areas
    • Smoking lounges
    • Cleaning materials
    • Emissions from trash
    • Pesticides
    • Odors and VOCs from paint, chalk, adhesives
    • Occupants
    • Occupants with communicable diseases
    • Dry-erase markers and similar pens
    • Insects and other pests
    • Personal care products
    • Stored gasoline, and lawn and garden equipment

     
     

  • Indoor Air Pollution and Health

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    While pollutants commonly found in indoor air are responsible for many harmful effects, there is considerable uncertainty about what concentrations or periods of exposure are necessary to produce specific health problems. People can also react very differently exposed to indoor air pollutants. Further research is needed to better understand which health effects occur after exposure to the average pollutant concentrations found indoors, and which effect results from the higher concentrations that occur for short periods of time. Health effects from indoor air pollutants may be experienced soon after exposure or, possibly, years later. 

    Immediate health 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 immediate 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, and hypersensitivity pneumonitis, may also show up soon after exposure to some indoor air pollutants. 

    The likelihood of immediate reactions 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. 

    Long-term 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 and work environment, even if symptoms are not noticeable.