Asthma in adults

What is Asthma?
Asthma affects the airways of the lungs (the bronchi) which causes the airways to become inflamed and swollen.

The bronchi are small tubes that carry air in and out of your lungs. If you have asthma, the bronchi are more sensitive than normal and certain substances, or triggers, can irritate them. Common triggers include house dust mites, animal fur, pollen, tobacco smoke, cold air, and chest infections.

When the bronchi are irritated, they become narrow and the muscles around them tighten, which can increase the production of sticky mucus,
or phlegm. This makes it difficult to breathe, and causes wheezing, coughing, and it may make your chest feel tight.

The severity of the symptoms of asthma differs from person to person,
from mild to severe. The narrowing of the airways is usually reversible -
occurring naturally, or through the use of medicines. However, for some
people with chronic (long-lasting) asthma, the inflammation may lead to an irreversible obstruction of the airways.A severe onset of symptoms is known as an asthma attack, or 'acute asthma exacerbation'. Asthma attacks can be life-threatening and may require hospital treatment.

Read Here - about 'Triggers' and the 'Different Kinds' of Asthma.
http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=36

You will also find links for 'Symptoms', Causes, Diagnosis
and other related information.