What is an asthma attack?
An asthma attack occurs when exposure to an allergen or other stimuli (such as exercise or cold air) causes mast cells (cells involved in the body's allergic response) in the tissue of an asthmatic's air passages to react by producing histamine, leukotrienes and other chemicals. These chemicals cause the following chain reaction:

• The smooth muscle of the bronchi goes into bronchospasm and tightens, constricting the airways.
  
  
• The tissues lining the airways - which are often inflamed in asthmatics - become more inflamed, further narrowing the airways.
  
  
• The inflamed tissues produce excess mucus that fills and obstructs the airways.

The combination of smooth-muscle constriction, tissue inflammation and mucus secretion significantly narrows the diameter of the airways. When this happens, air is trapped in the lungs, forcing the individual to expend great effort to move air in and out.

Because airways are narrowed during an asthma attack, a person may experience chest tightness, coughing, wheezing and shortness of breath. In severe cases, where breathing becomes very difficult and low blood oxygen levels occur, asthma attacks can be fatal. About 5,000 deaths each year are attributed to asthma, according to the American Academy of Allergy, Asthma and Immunology (AAAAI).

How many people have asthma?
The number of Americans with asthma has surged in recent years, with more than 20 million people of all ages reporting having asthma, according to the AAAAI. Greater numbers of children now have asthma than in the past, and poor children in urban environments have been hit particularly hard. However, Americans over age 65 make up the nation's largest group of asthmatics.

How does a person get asthma?
The source of asthma is not fully understood. Health-care professionals believe a combination of genetic and environmental factors determine whether or not a person becomes asthmatic. The AAAAI estimates that 40 percent of children who have asthmatic parents will develop asthma.

Can asthma be cured?
No, it can't - but it is a highly treatable condition. Various asthma medications can help prevent asthma attacks or treat them once they have begun. Asthmatics also can modify their environment and day-to-day behavior in ways that reduce the likelihood of an asthma attack. Some children with asthma may eventually see their symptoms subside as they grow older, but symptoms can recur at a later date. Others see their symptoms worsen as they age. Fortunately, proper diagnosis and treatment allows those with asthma to live full lives.

How is asthma diagnosed?
A physician is likely to use several methods to diagnose asthma. An individual's medical history - including prior breathing problems, allergies or skin conditions - may offer important clues. One's family history may also provide clues as asthma (like allergies) can run in families. But the primary means of uncovering asthma are diagnostic tests that measure an individual's airflow. These and other tests that may help ID asthma include: