Asthma Causes & Risk Factors

A combination of genetics and exposure to certain elements in the environment put people at the greatest risk of developing asthma for the first time.

The most common factors for developing asthma are having a parent with asthma, having a severe respiratory infection as a child, having an allergic condition, or being exposed to certain chemical irritants or industrial dusts in the workplace.

What Causes Asthma?

Scientists continue to explore what causes asthma, but we do know that these factors play an important role in the development of asthma:

  • Family history
    If you have a parent with asthma, you are three to six times more likely to develop asthma than someone who does not have a parent with asthma.
  • Allergies
    Some people are more likely to develop allergies than others, especially if one of their parents has allergies. Certain allergic conditions, such as atopic dermatitis (eczema) or allergic rhinitis (hay fever), are linked to people who get asthma.
  • Viral respiratory infections
    Respiratory problems during infancy and childhood can cause wheezing. Some children who experience viral respiratory infections go on to develop chronic asthma.
  • Occupational exposures
    If you have asthma, exposures to certain elements in the workplace can cause asthma symptoms. And, for some people, exposure to certain dusts (industrial or wood dusts), chemical fumes and vapors, and molds can cause asthma to develop for the very first time.
  • Smoking
    Cigarette smoke irritates the airways. Smokers have a high risk of asthma. Those whose mothers smoked during pregnancy or who were exposed to secondhand smoke are also more likely to have asthma. Learn more about the health effects of smoking with asthma
  • Air Pollution
    Exposure to the main component of smog (ozone) raises the risk for asthma. Those who grew up or live in urban areas have a higher risk for asthma.
  • Obesity
    Children and adults who are overweight or obese are at a greater risk of asthma. Although the reasons are unclear, some experts point to low-grade inflammation in the body that occurs with extra weight. Obese patients often use more medications, suffer worse symptoms and are less able to control their asthma than patients in a healthy weight range.

While these factors increase a person's risk for developing the disease, there are additional factors, such as poverty and lack of health insurance, that contribute to more asthma symptoms, emergency room visits and hospitalizations. Learn more about ways to improve asthma by understanding the risks related to exposure to things in the environment that are known to make asthma worse and management steps.

Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.

Page last updated: June 7, 2024

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