Top Allergy and Asthma Triggers

Identify the top triggers in and around your home, then follow our tips to help clear the air.
By: Stephanie Welch Alexander

© National Gardening Association

Photo By: Jupiterimages

Identifying Allergens

Allergies can strike at any time — not just in the spring or fall. Allergens (specific substances containing proteins that trigger sneezing, sniffling, watery eyes and rashes) cause the release of histamine in individuals carrying the antibody immunoglobulin E. In severe cases, a life-threatening condition called anaphylaxis can result. We'll help you idenity the top trigger in and around your home, so you can breathe better.


Plants have pollination cycles which are consistent from year to year — no surprise to allergy-sufferers. Weather conditions can also affect the amount of pollen in the air at any one time. The pollination season occurs earliest in the south and progressively later in northern regions. Trees pollinate earliest, followed by grasses and, finally, weeds. Thankfully, pollens (the small, round male cells of plants), traveling as far as 400 miles away and up to two miles in the air, vanish after the first frost.


Molds — parasitic, microscopic fungi lacking stems, roots or leaves — can make allergy-sufferers pretty miserable. As many as 250,000 mold spores can fit on one pin head, and they are found both indoors and outdoors. Levels peak in late summer and fall months.

Outdoor molds usually grow in moist shade areas (soil, decaying vegetation, leaves and rotten wood); indoor molds are usually found in dark, humid areas of the home (basements, cellars, attics and bathrooms). Mucor, Aspergillus and Penicillium are common indoor molds.


Proteins found in the saliva, pet dander and urine of furry animals can cause allergic reactions in 15 percent of the general population and in 20 percent to 30 percent of asthma sufferers. These proteins are carried on small, invisible particles that land on the lining of the eyes and nose or are inhaled directly into the lungs. Allergies can even flare up when the sufferer is exposed to dander carried on the clothing of pet owners.


These microscopic, sightless, eight-legged arthropods are natural inhabitants of indoor environments. Dust-mite droppings are the most common trigger of allergy and asthma symptoms.

Dust mites are found throughout the household and thrive in high humidity and where human dander is located, such as mattresses, pillows, bed linens, upholstery and carpeting.

Cockroaches, mice and rats are more than just unsightly nuisances — droppings and urine left behind are major triggers of asthma symptoms — particularly in densely populated urban neighborhoods. They are attracted to offices and homes where food and water are easily accessible.


Food allergies occur when a person's immune system overreacts to an ordinarily harmless food. The most common food allergies (responsible for up to 90 percent of all allergic reactions) are proteins in cow's milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts. The most common symptoms are hives, eczema, asthma and gastrointestinal symptoms.

Anaphylaxis, a systemic allergic reaction that can be fatal, is the most severe reaction and is marked by an initial feeling of warmth, flushing, tingling in the mouth and red, itchy rash. These symptoms are usually reversed with emergency measures, including antihistamines and injectable epinephrine administered under the care of a physician or allergist.

Household Products

This milky fluid (produced by rubber trees) is processed and manufactured into a variety of products. Those suffering from latex reactions have allergies triggered by dipped latex products.

Products that commonly cause reactions include gloves, balloons and condoms; although some individuals may suffer from reactions to rubber bands, erasers, rubber parts of toys, certain medical devices, latex clothing and elastic, feeding nipples and pacifiers. (Most latex paints are not a problem, since they do not contain natural latex.)

Insect Stings

Insect stings are responsible for inducing severe allergic reactions in at least 1 to 2 million people in the U.S. An estimated three percent of the population is susceptible to allergic reactions caused by insect stings, including those of yellow jackets, honeybees, paper wasps, hornets and fire ants.

For a small number of people, these stings can be life-threatening, resulting in anaphylaxis. Symptoms may include itching and hives, swelling of tongue or throat, breathing difficulty, dizziness and intestinal issues. In severe cases, a rapid fall in blood pressure may result in shock and loss of consciousness.

Pollutants and Lifestyle Exposures

Air pollutants such as tobacco smoke, wood smoke, diesel exhaust, ozone, perfumes, household cleaners, and airborne chemicals off-gassing from furniture and carpeting can trigger asthma and allergies. Also, strong odors or sprays (perfumes, household cleaners, cooking fumes, paints or varnishes).

Lifestyle factors, such as strenuous physical exercise, medications and anxiety and stress, also influence the onset and duration of allergic reactions.

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