BIOLOGICAL CONTAMINANTS

BIOLOGICAL CONTAMINANTS

Biological contaminants include bacteria, molds, mildew, viruses,
animal dander and cat saliva, house dust mites, cockroaches, and
pollen. There are many sources of these pollutants. Pollens
originate from plants; viruses are transmitted by people and
animals; bacteria are carried by people, animals, and soil and
plant debris; and household pets are sources of saliva and animal
dander. The protein in urine from rats and mice is a potent
allergen. When it dries, it can become airborne. Contaminated
central air handling systems can become breeding grounds for
mold, mildew, and other sources of biological contaminants and
can then distribute these contaminants through the home.

By controlling the relative humidity level in a home, the
growth of some sources of biologicals can be minimized. A
relative humidity of 3050 percent is generally recommended for
homes. Standing water, water-damaged materials, or wet surfaces
also serve as a breeding ground for molds, mildews, bacteria, and
insects. House dust mites, the source of one of the most powerful
biological allergens, grow in damp, warm environments.

Health Effects From Biological Contaminants

Some biological contaminants trigger allergic reactions,
including hypersensitivity pneumonitis, allergic rhinitis, and
some types of asthma. Infectious illnesses, such as influenza,
measles, and chicken pox are transmitted through the air. Molds
and mildews release disease causing toxins. Symptoms of health
problems caused by biological pollutants include sneezing, watery
eyes, coughing, shortness of breath, dizziness, lethargy, fever,
and digestive problems.

Allergic reactions occur only after repeated exposure to a
specific biological allergen. However, that reaction may occur
immediately upon re-exposure or after multiple exposures over
time. As a result, people who have noticed only mild allergic
reactions, or no reactions at all, may suddenly find themselves
very sensitive to particular allergens.

Some diseases, like humidifier fever, are associated with
exposure to toxins from microorganisms that can grow in large
building ventilation systems. However, these diseases can also be
traced to microorganisms that grow in home heating and cooling
systems and humidifiers. Children, elderly people, and people
with breathing problems, allergies, and lung diseases are
particularly susceptible to disease causing biological agents in
the indoor air.

Reducing Exposure to Biological Contaminants

Install and use exhaust fans that are vented to the outdoors in
kitchens and bathrooms and vent clothes dryers outdoors.

These actions can eliminate much of the moisture that builds up
from everyday activities. There are exhaust fans on the market
that produce little noise, an important consideration for some
people. Another benefit to using kitchen and bathroom exhaust
fans is that they can reduce levels of organic pollutants that
vaporize from hot water used in showers and dishwashers.

Ventilate the attic and crawl spaces to prevent moisture
buildup.

Keeping humidity levels in these areas below 50 percent can
prevent water condensation on building materials.

If using cool mist or ultrasonic humidifiers, clean appliances
according to manufacturer s instructions and refill with fresh
water daily.

Because these humidifiers can become breeding grounds for
biological contaminants, they have the potential for causing
diseases such as hypersensitivity pneumonitis and humidifier
fever. Evaporation trays in air conditioners, dehumidifiers, and
refrigerators should also be cleaned frequently.

Thoroughly clean and dry water-damaged carpets and building
materials (within 24 hours if possible) or consider removal and
replacement.

Water-damaged carpets and building materials can harbor mold and
bacteria. It is very difficult to completely rid such materials
of biological contaminants.

Keep the house clean. House dust mites, pollens, animal dander,
and other allergy causing agents can be reduced, although not
eliminated, through regular cleaning.

People who are allergic to these pollutants should use allergen
proof mattress encasements, wash bedding in hot (130 F) water,
and avoid room furnishings that accumulate dust, especially if
they cannot be washed in hot water. Allergic individuals should
also leave the house while it is being vacuumed because vacuuming
can actually increase airborne levels of mite allergens and other
biological contaminants. Using central vacuum systems that are
vented to the outdoors or vacuums with high efficiency filters
may also be of help.

Take steps to minimize biological pollutants in basements.

Clean and disinfect the basement floor drain regularly. Do not
finish a basement below ground level unless all water leaks are
patched and outdoor ventilation and adequate heat to prevent
condensation are provided. Operate a dehumidifier in the basement
if needed to keep relative humidity levels between 30 50 percent.

To learn more about biological pollutants, read Biological
Pollutants in Your Home issued by the U.S. Consumer Product
Safety Commission and the American Lung Association. For contact
information, see the section, Where to Go For Additional
Information.