Asthma is a lung disease that can be life threatening. Asthma is a chronic, or long-term, disease that can affect you for the rest of your life.

When asthma causes breathing problems, the person experiences an "asthma attack", or episode. During an attack, three major changes can take place in the lungs:

Cells in the air tubes make more mucus than normal. The mucus is thick and sticky and tends to clog up the air tubes.

Cells in the airways get inflamed, causing the air tubes to swell.

The muscles around the air tubes tighten.

These changes cause the air tubes to narrow and make it hard to breathe.

Asthma is a major public health problem in the U.S. and asthma prevalence has been on a steep rise since 1980. Though many cases of asthma probably go undiagnosed, health officials estimate that at least 20 million people in the U.S. have asthma, including 6.3 million children.

African-Americans have higher rates of asthma emergency room visits, hospitalizations and death than Caucasians. African-Americans visit the emergency room for asthma more than twice as often and are hospitalized for asthma more than three times as often.

Asthma is the most common chronic childhood disease, affecting 6.3 million children.

Nearly 1 in 13 school-aged children has asthma, and the rate is rising more rapidly in preschool aged children than in any other age group.

Approximately 4.2 million children had an asthma attack in the last year.

Asthma in children is the cause of almost 5 million physicians visits and more than 200,000 hospitalizations per year.

Asthma accounts for many nights of interrupted sleep, limitation of activity and disruptions to the family and caregiver routines. Asthma symptoms that are not severe enough to require a visit to the emergency room or to a physician can still be severe enough to prevent a child with asthma from living a fully active life.

Asthma attacks occur when something irritates the lungs and "triggers" an asthmatic reaction. Many things can trigger asthma. If you or a loved one has asthma, it's important to learn which triggers cause problems. Ask your doctor to help you.

Allergens and irritants trigger asthma for many people. Allergens are substances that do not cause problems for most people, but trigger allergic reaction in some people. During an allergy attack, the body releases chemicals called mediators that can trigger asthma episodes. Irritants, such as cigarette smoke, fragrances, paint and gasoline fumes can also trigger asthma. Exposure to irritants can stimulate receptors in the respiratory tract. The receptors send signals to the surrounding airways to constrict which can cause an asthma attack.

Once you know what triggers your asthma, you can take steps to reduce exposure to triggers and decrease the frequency and severity of your asthma attacks.

If you have asthma, you should know what you can do to reduce your chances of having an attack and what to do if you have an asthma episode. Talk to your doctor to set up an asthma management plan. Together, you and your doctor can monitor your asthma, determine common triggers and how to avoid them, and access the best medications to treat your asthma.

US Enviromental Protection Agency