Allergies are triggered
by substances called allergens. Each year, millions
of people suffer from seasonal allergy symptoms such
as nose and sinus congestion, itchy, runny nose and
itchy, watery eyes. However, many also suffer from perennial
allergies, which result in symptoms throughout the year.
Perennial allergies are triggered by indoor allergens,
including house dust mite droppings, animal dander,
cockroach droppings and indoor molds.
House dust mites
House dust is composed of small particles of plant and
animal material in the home. While this mix is not appealing
to us, microscopic creatures called house dust mites
thrive in it. The droppings of these mites are the most
common trigger of perennial allergy and asthma symptoms.
Dust mites are found throughout the house, but they
especially thrive in high humidity and in areas where
human dander (dead skin flakes) is located.
To reduce dust mites, it is important to keep humidity
below 50% throughout the home by using a dehumidifier
or central or window air conditioning. Wall-to-wall
carpeting should be removed as much as possible, especially
if it is laid over concrete floors. Hardwood, tile or
linoleum is better for people with allergies. Washable
throw rugs may also be used if they are regularly washed
in hot water or dry cleaned.
Because people spend more time in the bedroom than in
any other room, it is essential to reduce mite levels
there. Encase mattresses, box springs and pillows in
airtight, zippered plastic or special allergen-proof
fabric covers - all are available in many national stores.
Bedding should also be washed weekly in hot water (55°C)
and dried in a hot drier. For waterbeds, regularly wash
the mattress pad on top of the bed. Comforters and pillows
made of natural materials such as down feathers or cotton
should be covered with allergy-proof encasings.
Weekly vacuuming can help to further remove dust mites.
People with allergies should use a vacuum with a HEPA
(high-efficiency particulate) filter or a double bag,
since using a standard or water-filtered vacuum cleaner
stirs dust up into the air. Allergic individuals should
also wear dust masks.
Contrary to popular belief, people are not allergic
to an animal's hair, but rather, to a protein found
in the saliva, dander (dead skin flakes) or urine of
an animal with fur. These proteins are carried in the
air on very small, invisible particles, which can land
on the lining of the eyes or nose, or be inhaled directly
into the lungs. Usually, symptoms will occur quickly,
sometimes within minutes after exposure to the animal.
For some people, symptoms may build and become most
severe eight to 12 hours after they have had contact
with the animal.
A cat or dog produces a certain amount of allergen per
week, and this amount can vary from animal to animal.
All breeds are capable of triggering symptoms - there
are no "hypoallergenic" breeds of cats or dogs. People
with severe allergies can even experience reactions
in public places if dander has been transported on pet
The most effective way to combat symptoms of animal
allergy is to remove the pet from the home and avoid
any contact. Keeping an animal outdoors is only a partial
solution, since homes with pets in the yard still have
higher concentrations of animal allergens. Before you
get a pet, spend time with someone else's dog or cat
to determine if you're allergic. If you already have
an animal to which you or a family member is allergic,
try to place it with a caring, non-allergic friend or
relative. Although this separation can be difficult,
it is best for the health of you or your allergic family
member. You may also consider getting a pet such as
a turtle, hermit crab, fish, snake, or other animals
without fur or feathers.
If you cannot avoid exposure to the animal that causes
your allergy symptoms, try to minimize contact. Most
importantly, keep the pet out of the bedroom and other
rooms where people with allergies spend a great deal
of time. Some studies have demonstrated that bathing
dogs or cats on a weekly basis may reduce the amount
of allergens that are shed in the home. While dander
and saliva are the source of cat and dog allergens,
urine is the source of allergens from rabbits, hamsters
and guinea pigs; ask a non-allergic family member to
clean the animal's cage.
Vacuuming is not effective in decreasing animal allergens,
because it does not clean the lower levels of the rug.
In fact, it can stir up small allergen particles, which
can also move right through the vacuum. Using a HEPA
vacuum filter or double bags may help. As with dust
mites, the best solution is to have a hardwood floor,
tile or linoleum. Replace bedding and carpeting that
has animal dander in it. It can take weeks or months
for fabrics to come clean of allergens, and animal allergens
may persist for a year or more after the animal has
Cockroaches have been around for more than 300 million
years. Most live in warm, tropical climates, but various
species dwell in the offices and homes of humans. Cockroaches
are not just an unwelcome visitor in the home - a protein
in their droppings is a primary trigger of asthma symptoms,
especially for children living in densely populated,
urban neighborhoods. To reduce asthma symptoms, it is
important to eliminate cockroaches.
Block areas where roaches could enter the home, including
crevices, wall cracks, windows, woodwork or floor gaps,
cellar and outside doors and drains. Cockroaches need
water to survive and thrive in high humidity, so make
sure to fix and seal all leaky faucets and pipes. You
may also want to have a trained exterminator go through
the house when your family and pets are gone to eliminate
any remaining roaches.
Roaches feel less welcome in a clean, dry house. To
keep them from returning, keep food in tight-lidded
containers and put pet food dishes away after they are
done eating. Vacuum and sweep the floor after meals,
and take out garbage and recyclables frequently. Use
lidded garbage containers in the kitchen. Wash dishes
immediately after use in hot, soapy water, and clean
under stoves, refrigerators or toasters where loose
crumbs can accumulate. Wipe off the stove top and clean
other kitchen surfaces and cupboards regularly.
Indoor molds and mildew thrive in areas of the house
with increased humidity, such as damp basements and
bathroom windows. These molds send out small spores
that can trigger allergy symptoms.
Fortunately, indoor molds and mildew are easily eliminated
once you discover them. Use a cleaning solution containing
5% bleach and a small amount of detergent. If mold or
mildew are visible in carpeting or wallpaper, remove
these items from the house. Also, promptly repair and
seal leaking roofs or pipes. Never put carpeting on
concrete or damp floors, and avoid storing clothes,
papers or other items in damp areas.
Using dehumidifiers in damp basements may be helpful,
but they generally cannot control humidity throughout
the house. Empty the water in dehumidifiers and clean
units regularly to prevent mildew from forming. All
rooms, especially basements, bathrooms and kitchens,
require ventilation and consistent cleaning to deter
mold and mildew growth.
General consideration on indoor environmental control
Although you may be tempted to "air out" indoor allergens
from the home, opening the windows can bring outdoor
allergens such as pollen and mold spores into the house.
Instead, use air conditioning to clean, recirculate
and dehumidify the air in the home. You may also consider
using in-home air filters, many of which can be used
in conjunction with existing forced air cooling and
heating systems. These include HEPA filtering systems;
mechanical filters with standard disposable fiberglass
filters that should be changed monthly; permanent air
filters with baffles that should be cleaned periodically;
and electrostatic filters that utilize the natural electrostatic
properties of polypropylene and polyester to clean the
air. The filters' plates should be cleaned frequently,
or they may produce irritating ozone. Keep in mind that
although air filters and devices may be popular, none
have been scientifically proven to remove allergens
and decrease allergy or asthma symptoms. Similarly,
having air ducts cleaned, an expensive procedure, has
not been shown to be effective in reducing respiratory
symptoms. It is more effective to implement environmental
control measures to reduce allergens.
Those with allergies and asthma should also avoid airborne
irritants, including tobacco smoke, aerosols, paint,
perfumes, cleaning products or other strong odors or
Indoor environmental control measures should focus on
sites where allergens accumulate. By taking a thorough
history and performing allergy tests, if needed, your
allergist/immunologist can help you determine which
indoor allergens provoke your symptoms. Environmental
control measures differ for dust mites, animal allergens,
cockroaches and molds. To relieve your symptoms, your
allergist/immunologist may also prescribe appropriate
medications, such as antihistamines, decongestants or
asthma medications and allergy vaccine therapy.
Making changes to your indoor environment can take some
time. To begin, you may want to write down a priority
list. Progressive changes will produce an indoor environment
that is less allergenic, easier to clean, and healthier
for the whole family.