Asthma is a chronic (long-term) disease of the lungs that causes inflammation and narrowing (constriction) of the airways.

While the actual cause of asthma is not known, health experts believe that a combination of genetic and environmental factors can cause asthma or at least increase sensitivity to asthma triggers. These factors include:

  • family history
  • childhood viral respiratory infections
  • early allergen exposure
  • exposure to chemicals or smoke
  • living in urban settings
  • gender and age

Allergies are often associated with asthma. But not all people with allergies have asthma.

In this article, we review what researchers currently know about the risk factors and causes of asthma and what you can do to help avoid possible asthma triggers.

There are a number of factors thought to increase the risk of developing asthma. They include the following.

Family history

If one of your parents has asthma, you may be up to 3 to 6 times more likely to develop it, too. This is due to the underlying genetic components of asthma.

It’s thought that multiple genes may be involved in asthma development, and you can inherit these from your parents. You may be at a greater risk of developing asthma if your mother also has this lung disease.

Gender and age

Asthma is more common in children than adults. Boys are more likely to develop asthma than girls. However, women are more likely to develop adult-onset asthma.

Most children with asthma develop this condition before age 5.

Additionally, researchers note that African Americans are more likely to experience severe and uncontrolled asthma.


Sensitivity to allergens is often an accurate predictor of your potential to develop asthma. These allergens and irritants often include:

  • dust mites
  • pet dander
  • mold spores
  • toxic chemicals
  • pollen
  • foods

Allergens can trigger asthma attacks after you develop asthma. Atopic dermatitis (eczema) and hay fever (allergic rhinitis) are also considered risk factors. Additionally, the more allergies you have, the higher your risk of developing asthma.


Cigarette smoke leads to lung irritation, and people who smoke are at a higher risk of developing asthma. People exposed to secondhand smoke during childhood, or whose birthing parent smoked during pregnancy, are also more likely to have asthma.

Air pollution

This is the main component of smog, or ozone. Constant exposure to air pollution raises the risk of asthma.

Those who grew up or live in urban areas may have a higher risk of developing asthma. Additionally, researchers note more disparities among children with asthma living in cities, which could interfere with critical asthma care.

Occupational exposures

Exposure to certain chemicals, gases, or allergens may increase your risk of developing occupational asthma, or work-related asthma.

In fact, this asthma subtype has become so common in the United States that it’s estimated that 15 percent of all asthma cases may be job-related.

Some occupations that are considered higher risk for this type of asthma may include:

  • bakers
  • drug and detergent manufacturers
  • farmers
  • working with animals
  • plastic and metal workers
  • woodworkers
  • millers

Occupational asthma may take years to develop. In fact, it’s possible to experience this type of asthma even after you’re no longer exposed to the lung irritant(s).

Also, if you already have asthma, occupational exposure to fumes or chemicals may worsen your condition, leading to more asthma attacks.


Children (and especially adults) who are obese may be at a greater risk of asthma. It’s thought that low grade inflammation in the body from having extra body weight may contribute to this risk factor.

Also, if you already have asthma, your risk of disease exacerbation may increase if you develop obesity.

Viral respiratory infections

While some viral respiratory infections can cause wheezing, some children go on to develop asthma after recovering from their initial illness. This may be due to changes that these illnesses can create in a developing immune system.

Researchers have identified the two main conditions that cause asthma symptoms: inflammation and airway constriction. While symptoms may vary in intensity, they tend to be worse at night or in the early morning.


With asthma, the inside walls of the airways are swollen or inflamed. This inflammation makes the air passages particularly sensitive to irritants and asthma triggers. The swelling narrows the air passages, making it difficult for air to pass through the airways. This makes it hard to breathe normally.

Airway constriction

When the airways come into contact with certain asthma triggers, the muscles around the airways tighten. This causes the air passages to become even narrower. It also causes you to have a tight feeling in your chest. Some say it feels like a rope is being tightened around your chest.

Mucus can get lodged in the narrowed airways, causing more trouble breathing.

The triggers that cause the inflammation and airway constriction can vary from person to person. Understanding your triggers is essential to managing asthma.

Common asthma triggers include:

  • pollen
  • dust mites and cockroaches
  • mold
  • pet hair and dander
  • changes in weather, especially cold, dry air
  • viral respiratory infections, such as the common cold
  • smoke
  • stress and strong emotions
  • physical activity
  • an allergic reaction to food or sulfites
  • food preservatives
  • heartburn or acid reflux
  • certain medications, such as aspirin or beta-blockers
  • strong odors or perfumes

Work with your doctor to help figure out your triggers, and then come up with strategies to avoid them. Your asthma management plan may also include a combination of quick-relief and long-term controller medications to prevent asthma attacks.

Asthma is a chronic disease of the air passages in the lungs, and it may cause inflammation and constriction when you encounter certain triggers.

While the exact cause of asthma isn’t known, there are several risk factors that may contribute to its development, including a combination of genetic and environmental factors.

Triggers, such as airborne irritants and allergens, may cause the inflammation and airway constriction that characterize asthma. Understanding your triggers is essential to managing asthma, and you may also need ongoing treatments to help prevent an asthma attack.

Regardless of the possible causes of your asthma, you should see a doctor if you’re experiencing symptoms, such as wheezing, coughing, and shortness of breath. They can help you come up with an asthma action plan for long-term management.