Asthma, Part 1 — Introduction, Incidence and Symptoms

Asthma is a chronic condition that affects the lungs. When an individual has asthma, the passages from the nose to the lungs (the airways) are overly sensitive and become narrow, causing difficulty in breathing. Asthma is an excessive inflammatory response to "triggers", such as dust and other irritants, that cause changes in the airways.

There are certain things that commonly cause these changes to occur. These include atmospheric conditions (such as pollution, weather changes and cold temperatures), allergens in the environment (such as mold and animal dander from cats, dogs and guinea pigs), irritants such as cigarette smoke and dust, food allergies and respiratory infections (colds). An asthma "attack" consists of a relatively acute swelling and inflammation of the airways.

In addition, there is a reversible tightening of the tiny muscles that surround the airways. This is called bronchospasm (BRAHNK'-oh-spa-zem). Medications are used to prevent and reverse asthma and its exacerbations.

An individual with asthma does not have trouble with breathing all the time. Usually, a person with asthma will breathe quite normally. However, when a trigger is present in the environment, an asthma attack may result very quickly. Triggers are not the same for all people with asthma. Some people have reactions to several different triggers, while others may react to only a certain trigger. Indoor triggers, such as aerosol sprays and dust, can be just as problematic as outdoor triggers.

Common triggers include:

  • Tobacco smoke
  • Dust
  • Mold
  • Pollen
  • Exercise
  • Viral infections, such as colds
  • Animal hair and dander
  • Chemicals, both airborne and in food
  • Weather changes (especially sudden cold)
  • Strong emotional responses
  • Aspirin and other medications

Children are particularly vulnerable to asthma attacks, because their airways are narrower than those of adults. Because of this, triggers that would cause only a slight response in an adult may cause a severe response in a child.

Asthma attacks may have a sudden onset and can be very severe in children. Therefore, it is very important that asthma is diagnosed promptly and treated correctly. This might require that a child take asthma medications even without any difficulty breathing.
Preventing an asthma attack is preferable to treating a serious one.

Incidence and prevalence

Approximately 25 million Americans have asthma. The prevalence of asthma in the general population is one 1 case out of every 20 people. The prevalence has increased about 40 percent over the last decade. Asthma accounts for more school absences than any other chronic illness. Asthma accounts for more hospitalizations in children than any other chronic illness. In most children's hospitals in the U.S., it is the most common diagnosis on admission.

Despite advances in our understanding of asthma and the development of new therapeutic strategies, the morbidity and mortality due to asthma increased between 1980 and 1995. During that period in the U.S., the mortality due to asthma increased in all age, race and gender groups. The mortality now stands at more than 17 deaths per 1 million population annually (5000 deaths per year). From 1975 to 1993, the mortality nearly doubled among children between the ages of 5 and 14.

Before puberty, asthma is diagnosed more commonly among boys than girls, by a 3-1 ratio. During adolescence, the rates become equal. Adult-onset asthma is diagnosed more commonly among women than men. Most children develop asthma before age 5, and more than half of these children develop it before age 3.

Worldwide, the incidence of childhood asthma has increased in recent years. This is thought to be linked to environmental factors, including air pollution.


When an individual with asthma is not having an asthma attack, there are no symptoms of the disease. However, during an asthma attack, the person might have difficulty breathing, breathe very rapidly or have a cough. Shortness of breath, even at rest, can be another symptom of asthma.

During an asthma attack, a child might exert extra effort to breathe, using "accessory" muscles around the chest and neck. This exertion can cause discomfort or pain. Wheezing and a constant, "barking" kind of cough may be another signs of an asthma attack. Some kids have a cough even when they are feeling well. A persistent nighttime cough is a common sign of asthma, and may appear without other symptoms.

Asthma is diagnosed with the information that the patient and family provide, physical examination and additional diagnostic studies. The doctor may hear wheezing. An instrument called a spirometer (spi-RAH'-mi-tur) helps the doctor make the diagnosis of asthma. At home, the patient or parents might use another instrument called a "peak flow meter", which measures how well air is moving in and out of the lungs. A sudden drop in the peak flow readings may signal an imminent asthma attack.

For more information

Asthma, Part 2 — Treatment, Side Effects and Implications for School

The American Lung Association®

61 Broadway, 6th Floor
NY, NY 10006

Asthma and Allergy Foundation of America

Contributed by:

Juan Ruiz, MD
Assistant Professor
Department of Pediatrics
University of Kansas Medical Center

Kathy Davis, MSEd, PhD
Associate Professor
Project Director, Connected Kansas Kids
Director, KU Kids Healing Place
University of Kansas Medical Center