Help Center - Indoor Air Quality
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What
Causes Indoor Air Problems?
1. Pollutant
Sources
There are many sources of indoor air pollution
in any home, including:
- Combustion
sources such as oil, gas, kerosene, coal,
wood, and tobacco products
- Building materials and furnishings including
asbestos-containing insulation, wet or
damp carpet, and cabinetry or furniture
made of certain pressed wood
- Products
for household cleaning and maintenance,
personal care, or hobbies
- Central
heating and cooling systems and humidification
devices
- Outdoor
sources such as radon, pesticides, and
outdoor air pollution
The
importance of any single source depends
on how much of a given pollutant it gives
off and how hazardous those pollutants are.
In some cases, factors such as how old the
source is and whether it is properly maintained
are significant.
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.
2.
Amount of Ventilation
If too little outdoor air enters a home,
pollutants can accumulate to 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."
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Indoor
Air and Your Health
Health
effects from indoor air pollutants 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, hypersensitivity pneumonitis,
and humidifier fever, 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
from person to person. Some people can become
sensitized to biological and chemical pollutants
after repeated exposures
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
a person is away from the home and return
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 the 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. More information on potential
health effects from particular indoor air
pollutants is provided in the section, "A
Look at Source-Specific Controls."
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Improving
Air Quality Problems
There are three basic strategies to improving
your indoor air quality:
1.
Source Control
Usually the most effective way to improve
indoor air quality is to eliminate individual
sources of pollution or to reduce their
emissions. Some sources, like those that
contain asbestos, can be sealed or enclosed;
others, like gas stoves, can be adjusted
to decrease the amount of emissions.
2.
Ventilation Improvements
Another approach to lowering the concentrations
of indoor air pollutants in your home is
to increase the amount of outdoor air coming
indoors. Most home heating and cooling systems,
including forced air heating systems, do
not mechanically bring fresh air into the
house. Opening windows and doors, operating
window or attic fans, when the weather permits,
or running a window air conditioner with
the vent control open increases the outdoor
ventilation rate. Local bathroom or kitchen
fans that exhaust outdoors remove contaminants
directly from the room where the fan is
located and also increase the outdoor air
ventilation rate.
3.
Air Cleaners
There are many types and sizes of air cleaners
on the market, ranging from relatively inexpensive
table-top models to sophisticated and expensive
whole-house systems. Some air cleaners are
highly effective at particle removal, while
others, including most table-top models,
are much less so. Air cleaners are generally
not designed to remove gaseous pollutants.
The
effectiveness of an air cleaner depends
on how well it collects pollutants from
indoor air (expressed as a percentage efficiency
rate) and how much air it draws through
the cleaning or filtering element (expressed
in cubic feet per minute). A very efficient
collector with a low air-circulation rate
will not be effective, nor will a cleaner
with a high air-circulation rate but a less
efficient collector. The long-term performance
of any air cleaner depends on maintaining
it according to the manufacturer's directions.
Another
important factor in determining the effectiveness
of an air cleaner is the strength of the
pollutant source. Table-top air cleaners,
in particular, may not remove satisfactory
amounts of pollutants from strong nearby
sources. People with a sensitivity to particular
sources may find that air cleaners are helpful
only in conjunction with concerted efforts
to remove the source.
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