What Causes Asthma? Surprising causes in our environment and homes including pollution, dust, insects, and foods we eat.

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Asthma is a condition that causes a person’s airways to swell and become smaller. Often, people suffering with asthma will have episodic bouts of coughing, wheezing, and a sensation of not being able to catch one’s breath. Though asthma is treatable, the condition is not curable. Asthma ranges in severity from occasional and mild symptoms to severe, life-threatening attacks.

Environmental Causes: Pollution, Dust, and Pollen

Studies suggest that many types of air pollution around us may trigger more frequent asthma attacks. This means that not only people living in overcrowded cities with lots of car exhaust, but also those living in areas where there is a lot of airborne dust or exhaust from factories, may be at risk. In a study of human volunteers with asthma, it was shown that a common airborne irritant, sulpher dioxide, can cause narrowing of the airways in lungs. In addition, areas with high levels of ozone may also cause more frequent attacks.

Those suffering from asthma should take care to heed daily warnings on air pollution levels. Typically in many large cities, these are reported in the newspaper or television. Asthmatics with severe, symptomatic disease may consider staying away from congested freeway routes and dense urban centers on these days.

Another common irritant to asthmatics is released form many of the plants and trees around us. Namely, pollen is one of the most common irritants to asthmatics. Typically, patients that suffer from asthma report worsening of symptoms in the spring to summer months. Often, even cut grass may serve as a potential trigger for an asthma attack. Care should be taken when considering contact with areas that may have a higher pollen output such as parks, botanical gardens, and orchards during these months.

Causes in Our Homes: Mold, Animal Dander, and Insects

Some of the most severe asthma attacks may occur in a person’s own home. Though it is nearly impossible to eliminate all asthma triggers from our homes, knowing about certain risk factors is important.

Many types of mold and spores can trigger an attack. Moist areas such as bathrooms, cellars, and basements are particularly prone to accumulate moisture and therefore mold. Eliminating the excess moisture and mold may be one way to reduce exposure.

Our pets are another common source of asthma triggers in the form of animal dander. Though no dogs or cats are totally free of dander, certain breeds seem to produce less and may be less of an irritant. Selecting a breed of cat or dog that sheds less may reduce your incidence of new asthma attacks.

Insects may also be an unexpected source of lung irritant. Many insects such as cockroaches and dust mites have been associated with a higher incidence of asthma attacks. Making certain that insects are controlled around your home is an effective way to avoid an additional trigger.

Physical Activity and Asthma

Studies show that many people experience acute asthma attacks during or directly after vigorous exercise. This may also be compounded by brisk inhalation of cool air. Airways may constrict rapidly when oxygen requirements are high, causing a sudden and severe need for bronchial dilation. Care should be taken when engaging in strenuous activity under these conditions.

Acid Reflux May Cause Asthma

Gastroesophageal reflux disease (GERD), known more commonly as acid reflux, is well known to exacerbate the symptoms of asthma in many sufferers. When stomach acid regurgitates, a small amount, known as a chemical irritant, may enter the lungs. This causes a reaction that may trigger an asthma attack. Acid reducing medications may offer some symptomatic relief.

Foods We Eat and Asthma

Many sufferers of asthma may also suffer from an underlying food allergy. Exposure to foods that cause an allergic reaction, however small, may be beneficial. Common foods that may cause an inflammatory response include:

  • Nuts
  • Soy
  • Shellfish and fish
  • Wheat
  • Sulfites
  • Dairy products
  • Eggs


  1. Mayo Clinic: “Asthma - Causes.” Accessed electronically from https://www.mayoclinic.com/health/asthma/DS00021/DSECTION=causes on September 19, 2010.
  2. Hello Life: “Eat Right to Avoid Asthma.” Accessed electronically from https://www.hellolife.net/explore/asthma/eat-right-to-avoid-asthma-foods-to-avoid-to-reduce-asthma-symptoms/ on September 19, 2010.
  3. HE&W: “Airborne Environmental Pollutants and Asthma.” Accessed electronically from https://www.agius.com/hew/resource/asthma.htm on September 19, 2010.