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Asthma

What is asthma?

Asthma is a chronic (long-term) disease that makes it hard to breathe. Asthma can't be cured, but it can be managed. With proper treatment, people with asthma can lead normal, active lives.

If you have asthma, your airways (breathing passages) are extra sensitive. When you are around certain things, your extra-sensitive airways can:

Become red and swollen - your airways get inflamed inside. They fill up with mucus. The swelling and mucus make your airways narrower, so it's harder for the air to pass through.

Become "twitchy" and go into spasm - the muscles around your airways squeeze together and tighten. This makes your airways narrower, leaving less room for the air to pass through.

The more red and swollen your airways are, the more twitchy they become.

Normal airways
Airways of a person without asthma
Airways of a person with asthma - redness and swelling (inflammation) Airways of a person with asthma - tightened muscles (bronchospasm)
Illustration of normal airways Illustration of inflamed airways Illustration of airways with tightened muscles
In people without asthma, the muscles around the airways are relaxed, allowing the airways to stay open. There is no swelling or mucus inside the airways. In people with asthma, the inside of the airways can get red, swollen, and filled with mucus. In people with asthma, the muscles around the airways can spasm and squeeze tighter. This leaves less room for air to pass through.
What sets off your asthma symptoms?

Many different things can set off your asthma symptoms. Each person with asthma has her own set of asthma inducers and asthma triggers.

Asthma inducers: If you breathe in something you're allergic to- for example, dust or pollen- or if you have a viral infection- for example, a cold or the flu- your airways can become inflamed (red and swollen).

Asthma triggers: If you breathe in an asthma trigger like cold air or smoke, or if you exercise, the muscles around your airways can go into spasm and squeeze together tightly. This leaves less room for air to pass through.

It's important for every person with asthma to know what they triggers and inducers are, so they can avoid them.

What causes asthma? Who is at risk of getting it?

Doctors know that there are some things that make a person more likely to get asthma:

Family history: if people in your family have allergic diseases like asthma, hay fever (allergic rhinitis), or eczema, there is a higher chance you will have asthma.

Air pollution indoors and outdoors: some research shows that people who live near major highways and other polluted places are more likely to get asthma. Also, kids who grow up in a home with mould or dust may be more likely to get asthma.

Work-related asthma (occupational asthma): People who work in certain types of jobs can get asthma from things they work with. For example:

  • Laboratory workers can get asthma from lab animals: rats, mice, guinea-pigs
  • Spray painters can get asthma from isocyanates
  • Grain handlers can get asthma from grain dust
  • Crab processors can get asthma from crab dust

Learn more about work-related asthma, including occupational and work-exacerbated asthma. In our section on work-related asthma, we explain who is at risk for work-related asthma, signs and symptoms of work-related asthma, and more.

Second-hand smoke: Kids whose mothers smoked while pregnant, who grow up in a smoky house, or whose grandmothers smoked, are all more likely to get asthma. Read more about how smoking while pregnant hurts the baby



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