Asthma - Risk Factors - Risk Factors

Your environment or occupation, your family history or genes, other medical conditions, your race or ethnicity, or your sex may raise your risk for developing asthma.

Asthma affects people of all ages, but it often starts during childhood. Sometimes asthma develops in adults, particularly women. This type of asthma is called adult-onset or late-onset asthma.

Environment or occupation

Things in your environment, including at work or home, may raise your risk of developing asthma or make asthma symptoms worse.

  • Exposure to cigarette smoke in the womb or in a child’s first few years raises the risk of developing asthma symptoms early in life. This exposure may also affect lung growth and development.
  • Exposure to different microbes in the environment, especially early in life, can affect how the immune system develops. These effects on the immune system may either increase or protect against the risk of developing asthma.
  • Exposures that occur in the workplace, such as chemical irritants or industrial dusts, may also raise the risk of developing asthma in susceptible people. This type of asthma is called occupational asthma. It may develop over a period of years, and it often lasts even after you are no longer exposed.
  • Poor air quality from pollution or allergens may make asthma worse. Pollutants may include traffic-related air pollution. Allergens in the air may include pollen, dust, or other particles.

Family history and genes

Genes may play a role in the development of asthma because they affect how the immune system develops. More than one gene is likely involved. You inherit genes from your parents. Having a parent who has asthma, especially if the mother has asthma, increases the risk that a child will develop asthma.

Other medical conditions

Asthma is often linked to other medical conditions, such as:

  • Allergies. Asthma is usually a type of allergic reaction. People who have asthma often have other types of allergies. They may have food allergies or get a runny or stuffy nose from pollen. You may be at higher risk for developing asthma if you had allergic reactions in early childhood to substances in the air, such as pollen, dander, mold, or dust. The more things you are allergic to, the higher your risk of asthma.
  • Obesity can increase the chances of developing asthma or worsening asthma symptoms. This may be because people who have obesity can have inflammation or changes in the immune system.
  • Respiratory infections and wheezing. Young children who often have respiratory infections caused by viruses are at highest risk of developing asthma symptoms early in life.

Race or ethnicity

African Americans and Puerto Ricans are at higher risk of asthma than people of other races or ethnicities. African American and Hispanic children are more likely to die from asthma-related causes than non-Hispanic white Americans.


Among children, more boys than girls have asthma. Among teens and adults, asthma is more common among women than men.