I

indoor air quality The average American spends
20 hours or more of each day in various indoor
environments such as work, school, and home.
Because the air they breathe recirculates, it accu-
mulates pollutants. Indoor air may contain two to
five times as much pollution as outdoor air. Health
experts believe this contributes to the rise over
recent decades in ASTHMAand other respiratory
diseases. Indoor air pollutants may be visible,
linger as odors, or remain undetected. The risk to
health does not necessarily correlate with the abil-
ity to detect the pollutant; some of the most haz-
ardous substances (such as carbon monoxide)
have no smell or visible presence.

COMMON INDOOR AIR POLLUTANTS

aerosol products animal dander
asbestos in older structures BACTERIA
body fragrances CARBON DIOXIDE
carbon monoxide cleaning solutions
dust dust mites
formaldehyde glues, paints, and solvents
lead mercury
molds, mildew, and fungi ozone
particulates pesticides
radon TOBACCOsmoke
viruses volatile organic
compounds

Ventilation and outdoor air exchange are
important for bringing fresh air into the building
or home and releasing indoor pollutants so they
can disperse. This helps reduce exposure to harm-
ful substances and lower the risk of resulting
health conditions. Federal regulations establish
ventilation and air exchange rates for commercial
buildings. Indoor air also may be too dry or too

moist (humid), requiring humidification or dehu-

midification to make it more comfortable to

breathe. Humid air supports the growth of molds

and fungi, which can cause hypersensitivity

response, ALLERGIC RHINITIS, chronic BRONCHITIS, and

other upper respiratory tract conditions. Improp-

erly cleaned humidifiers also can become patho-

genic reservoirs, harboring and dispersing colonies

of molds and bacteria. Central home heating sys-

tems have filters that homeowners or residents

must periodically change.

The US Environmental Protection Agency

(EPA) administers regulations and standards for

indoor air quality, and recommends a three-prong

approach:

1. Control pollutants at their sources: This may
   include no smoking indoors and installing car-
   pets that do not contain VOCs,


2. Ventilate: Open windows and circulating fans
   move air containing pollutants outside and
   bring in fresh air.


3. Clean the air: Air cleaners and filters use vari-
   ous methods to extract specific kinds of pollu-
   tants from the air. The EPA cautions that air
   cleaners cannot substitute for proper ventila-
   tion and source control as the primary mainte-
   nance measures for clean air. Some air cleaners
   may add different pollutants to the air, such as
   particulates or ozone.

See also BUILDING-RELATED ILLNESS; ENVIRONMENTAL

CIGARETTE SMOKE; LEGIONNAIRES’ DISEASE; RADON

EXPOSURE; SICK BUILDING SYNDROME.

influenza prevention INFLUENZA, commonly

called the flu, is an upper respiratory INFECTION

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