Asthma is a chronic lung condition. Inflammation, increased mucus, and muscle tightening cause the airways to narrow. 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. Nearly 23 million Americans, including 7 million children, suffer from this condition.
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. Immune cells secrete substances that provoke further inflammation. Second, the muscles around the airways 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:
- aspirin 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 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
Smoking is also very irritating to the lungs and can contribute to asthma attacks. People with asthma should not smoke.