Asthma Triggers

in Asthma, Basics
Published: September 2, 2010
Photo: Thinkstock

It is important to know what triggers your asthma, so that you can avoid that trigger as much as possible. The following are some potential triggers, and advice on how to avoid them.

Pet dander

If animal dander, for example, from a cat or dog, triggers your asthma, experts agree the best thing to do is avoid having a pet in the home.

When visiting friends or relatives, ask that they put the animal in another room and that all furnishings and carpets be vacuumed before you arrive. Note that for some people, reactions will still occur. In this case, visiting that home should be avoided.


Allergies to pollens are seasonal: in the spring, the biggest culprit is trees. Summertime is when grass pollinates, and the fall is when ragweed sufferers feel symptoms.

If your asthma is triggered by any of these pollens, you’ll want to do your best to avoid them:

  • Stay indoors during high pollen counts: typically in the morning, and on dry, breezy days.
  • Keep your windows closed, especially during the day. If it’s hot outside, use an air conditioner instead.
  • Don’t hang laundry outside to dry. It will collect pollen.
  • Wash your hands and other exposed skin when you come inside, and shower before going to bed to rinse pollen from your skin and hair.
  • Invest in a vacuum with a certified HEPA filter, and vacuum often. Also wipe with a damp cloth rather than sweeping.
  • If you have a pet, wipe down its fur, which gets laden with pollen, before it comes inside.

Molds are a type of fungus that grow in damp, humid areas. Both indoor and outdoor mold can trigger asthma. To avoid mold growing inside your house, keep the humidity in your house between 40 and 45 %, always use bathroom and kitchen fans, and wipe up any spills and fix water leaks immediately.

Outdoor molds can be found in piles of grass or leaves and where there is stagnant water. Remove these from around your home.

Dust mites

Dust mites are microscopic insects that live in our carpets, mattresses, stuffed animals and furniture. Their feces are highly allergenic, and trigger asthma in many people.

While dust mites can never be completely eliminated in your home, there are ways to reduce exposure:

  • Dust mites thrive in humid environments, so keep humidity in your home between 40 and 45 per cent.
  • Encase your mattress, duvet and pillows in dust mite-proof covers.
  • Wash bedding, including fabric mite-blocking covers, weekly in water at least 120 degrees F.
  • About every eight weeks, place stuffed animals in the freezer for 24 hours.
  • Choose hardwood, tile or vinyl flooring when possible, and minimize plush furnishings.
Cigarette smoke

Both direct and second hand smoke will trigger asthma in most people. If you have asthma and smoke, now is the time to quit.

If you’re not a smoker, it’s still important to reduce your exposure to cigarette smoke. Don’t allow anybody to smoke in your house or car, and avoid places where people are, or have been smoking.


Air pollution and smog can make asthma worse. Smog results when pollution from automobiles, factories and power plants is struck by sunlight. Keep an eye on smog advisories in your area. On smog-alert days, do your best to stay indoors. Experts advise all people to limit outdoor exercise on days with very low air quality.


Scents from perfumes or fragrances in personal care products, such as shampoo, can trigger asthma in some people. If this is the case, avoid products that list “perfume” or “fragrance” in the ingredients.

Viral infections

Asthma is often triggered by viral infections, such as colds. This is particularly true in young children. Frequent hand-washing, as well as avoiding touching your nose and mouth, are recommended.

People with asthma are also encouraged to get the flu shot.


While it’s important for people with asthma to exercise, it can also be an asthma trigger. See Exercise and Asthma.

See Also:

Outdoor Allergy Hub: Pollens, Mold, Gardening
Why So Many Allergies Now?
Pet Allergies: A Gander at Dander