General Introduction
Healthy lungs are essential to feeling good. The lungs are the organs we use to breathe. They work by taking oxygen from the air we breathe in and then exchanging it for carbon dioxide, a deadly waste product made by the cells of the body. Once this exchange has taken place, we can then get rid of the carbon dioxide by breathing it out, or exhaling.

Asthma is a disease that affects the lungs and the airways that deliver air to the lungs. It causes periodic attacks of wheezing and difficult breathing. An attack occurs when the airways become inflamed in response to a trigger, such as dust, mold, pets, exercise, or cold weather. However, some attacks start for no apparent reason. Triggers may inflame the airways to the lungs, allowing disease-fighting cells to accumulate and causing swelling in the lungs. In addition, the airways may become blocked or obstructed when the muscles surrounding the lungs tighten or go into spasm. This keeps air from circulating freely in the lungs. Or, mucus may clog and narrow the airways in the lungs, making breathing even more difficult.

During an attack, the walls of the airways become inflamed, and the mucous membrane covering the walls becomes swollen with fluid. Sticky mucus fills the remaining space, making it difficult to breathe. Because air cannot flow in and out of the lungs freely, a whistling or wheezing sound may be heard.

During severe attacks, wheezing may stop because there is too little air moving to make any noise.

Attacks can be mild, moderate, or severe, and can last for a few minutes, a few hours, or several days. They can occur anywhere and at any time. Many occur at night. Sometimes, there are warning signs that an attack is about to happen, but sometimes there aren't.

Symptoms of Asthma
Symptoms can vary among people. Usually there is scratchy throat, or tightness in the chest, followed by a cough, wheezing, or shortness of breath.

Allergies and Asthma
Allergy is the leading cause of asthma, and about 90% of children under the age of 10 with asthma have allergies. About 70% of people under 30 with asthma and 50% of those over 30 with asthma also have allergies. Allergy is likely to be a contributing factor to asthma if:

Fast Facts about Asthma

• If you have asthma, you're not alone ... Asthma affects nearly 12 million people in America
  
• Although many people think asthma is "no big deal," about 5,000 Americans die of asthma each year.
  
• African-Americans are nearly three times as likely as whites to die of asthma
  
• Each year, asthma costs more than $4.6 billion in medical care and time lost from school or work
  
• Asthma is the number one reason why children miss school and the leading reason why children are admitted to the hospital
  
• More children than adults have asthma. This is because some children "outgrow" their asthma attacks when they grow up.
  
• Percentage of people with asthma by age: