In this condition factsheet:
The Facts on Asthma
Asthma is a chronic lung condition. Inflammation, increased mucus, and muscle tightening cause the airways to narrow, and as a result, air can't move through the lungs as well as it should, which makes it difficult to breathe.
For reasons we do not completely understand, asthma is becoming more common each year, especially in children. According to the World Health Organization (WHO), about 300 million people in the world have asthma. Over 3 million Canadians suffer from this condition.
Causes of Asthma
The cause of asthma is poorly understood, but it may be partly inherited. Everyone's lungs are sensitive to different things such as pollen, air pollution, or strong chemicals. In simple terms, people with asthma have lungs that are more sensitive than average.
There are 3 processes in the lungs that produce asthma symptoms. First, the inner linings of the airways become inflamed. They swell up, leaving less room for air to pass through. Second, the muscles around the airways can tighten, closing them further. Finally, the airways produce mucus in response to the inflammation, clogging the shrunken tubes.
Asthma is in part an allergic response. It may be triggered by some external substance that particularly irritates your lungs. These triggers are often small protein particles called allergens. Some people are sensitive to more than one trigger. Common allergens include:
- animal dander
- cockroach particles
- grass, tree, and ragweed pollen
- house dust mites
Other people can get an asthma attack from something they swallow rather than breathe. Examples of these triggers include:
- ASA* and other anti-inflammatory medications
- nuts or shrimp
- preservatives found in some drinks or foods
While most people develop asthma as children, adults can become asthmatic by being exposed to allergens, irritants, or occupational sensitizers for a long time. People who work with the following products may be at increased risk:
- cotton and flax
- foams and paints
- grains and cereals
- insulation and packaging materials
Asthma attacks can also be triggered by non-allergic irritants, such as:
- laughing hard, crying, shouting
- smog and smoke
- strong smells (e.g., paint fumes, perfumes, cleaning products)
- suddenly breathing cold air
- vigorous exercise
- viral infections such as the common cold or the flu
Symptoms and Complications of Asthma
Some children feel an itch on the back of the neck just prior to an asthma attack. Some people have some warning sign that they can learn to recognize. Warning signs include sore throat, dark circles under the eyes, feeling tired or irritable, or a change in the colour of your face.
Asthma varies in its severity. Some people experience asthma symptoms continuously, while others experience symptoms only if exposed to triggers. Regardless of the severity, typical asthma symptoms include:
- chest tightness
- shortness of breath
With more severe asthma, these symptoms may occur at night.
Wheezing is the best-known asthma symptom, but not everyone with asthma wheezes. Some people only have a cough that doesn't seem to go away.
A really severe asthma attack is life-threatening. Even if some air is coming in, deadly carbon dioxide builds up in the blood. If you or a family member can't breathe and the normal medication isn't working, call 9-1-1 or your local emergency number.