into the air are the primary cause of indoor air quality problems
in homes. 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 home. High temperature and humidity levels can also
increase concentrations of some pollutants.
Pollutant Sources
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 pressed 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 air 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 unvented 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 pollutant concentrations can remain in the air
for long periods after some of these activities.
Amount of Ventilation
If too little outdoor air enters a home, pollutants can
accumulate o levels that can pose health and comfort problems.
Unless they are built with special mechanical means of
ventilation, homes that are designed and constructed to minimize
the amount of outdoor air that can leak into and out of the home
may have higher pollutant levels than other homes. However,
because some weather conditions can drastically reduce the amount
of outdoor air that enters a home, pollutants can build up even
in homes that are normally considered leaky.
