Asthma

What Is Asthma?

Asthma is a chronic, or long-term, lung disease that can have lifelong effects and can be life threatening.

Asthma causes breathing problems, called asthma attacks or episodes, by blocking the airways in the lungs, causing them to get less air than normal. Symptoms of an asthma attack can be difficulty with breathing, a tight feeling in the chest, coughing, and wheezing. Asthma can develop quickly and can range from being a mild discomfort to a life-threatening attack if breathing stops completely. Asthma problems are often separated by symptom-free periods.

What Happens in an Asthma Attack?

During an asthma attack, three major changes can take place in the lungs:

1. Cells in the air tubes make more mucus than normal. This mucus is very thick and sticky, and tends to clog up the tubes. 
2. Cells in the airways get inflamed, causing the air tubes to swell.
3. The muscles around the air tubes tighten.

These changes cause the air tubes to narrow, which makes it difficult to breathe.

Who Gets Asthma?

In the United States, about 15 million people of all ages, races, and nationalities have asthma. Asthma can occur at any age but is more common in children than adults. The impact of asthma falls disproportionately on African-American and certain Hispanic populations and appears to be particularly severe in urban inner cities. Many cases of asthma likely go undiagnosed. 

How Are Children Affected by Asthma?

Nearly 1 in 13 school-age children or 4.8 million have asthma, and that rate is rising more rapidly in preschool-age children than in any other group. Asthma accounts for one-third of all pediatric emergency room visits and is the fourth most common cause for physician office visits.

Asthma is one of the leading causes of school absenteeism, accounting for more than 10 million missed school days per year. Asthma also accounts for many nights of interrupted sleep, limitation of activity, and disruptions of family and caregiver routines. Asthma symptoms that are not severe enough to require a visit to an emergency room or to a physician can still be severe enough to prevent a child with asthma from living a fully active life.

Children breathe more air, eat more food, and drink more liquid in proportion to their body weight than do adults. Their developing bodies may be more susceptible to environmental exposures than those of adults. In a typical day, children may be exposed to a wide array of environmental agents at home, in day care centers and schools, and while playing outdoors.

Read the EPA publication, "IAQ Tools for Schools:  Managing Asthma in the School Environment." and visit EPA's Schools Web site.

What Triggers Asthma Attacks?

Asthma attacks can be caused by "asthma triggers," which irritate the lungs. Two major categories of asthma triggers are allergens and irritants.

Allergens are substances that cause no problem for a majority of people but that trigger an allergic reaction in some people. During an allergy attack, the body releases chemicals called mediators. These mediators often trigger asthma episodes.

Irritants such as cold air, cigarette smoke, industrial chemicals, perfume, and paint and gasoline fumes can trigger asthma. These irritants probably trigger asthma symptoms by stimulating irritant receptors in the respiratory tract. These receptors, in turn, cause the muscles surrounding the airway to constrict, resulting in an asthma attack.

Viral infections are the leading cause of acute asthma attacks. Surprisingly, bacterial infections, with the exception of sinusitis, generally do not bring about asthma attacks.

Because Americans spend up to 90% of their time indoors, exposure to indoor allergens and irritants may play a significant role in triggering asthma attacks.

If I Have Asthma, What Can I Do?

If you or a loved one have asthma, it's important to learn which triggers are a problem. Ask your doctor to help. Your doctor may suggest keeping an asthma diary or recommend skin testing for allergies. Once asthma triggers are known, actions can be taken to prevent asthma attacks, or make them less severe, by cutting down exposure to the triggers.

Consult your physician to set up an asthma management plan to help monitor your asthma, take appropriate medication for your asthma, and identify and avoid your asthma triggers. Following your asthma management plan will help keep your asthma under control.

National Academy of Sciences Report "Clearing the Air: Asthma and Indoor Air Exposures"

The Environmental Protection Agency (EPA) asked the National Academy of Sciences (NAS) to undertake an assessment of the role of indoor air quality in the growing asthma problem. EPA asked NAS to characterize the state of the science on health impacts and prevention strategies, and to provide recommendations on needed research. In response to this request, the National Academy of Sciences Institute of Medicine has issued a report, "Clearing the Air: Asthma and Indoor Air Exposures," on the role of indoor environmental pollutants in the development and exacerbation of asthma. The report affirms the administrator's asthma initiative to educate the public about the ways they can help control asthma by managing indoor air quality. The report concludes that exposure to indoor pollutants is an important contributor to the asthma problem in this nation. Asthma sufferers should consult with their doctor about reducing their exposure to secondhand smoke, dust mites, pet dander, molds, and cockroaches.

For more information, read the EPA's brochure "Clear Your Home of Asthma Triggers: Your Children Will Breathe Easier"