Asthma Health Article

Demographics

Asthma affects about 17 million Americans, including nearly five million children. Asthma usually begins in childhood or adolescence, but it also may first appear in adulthood. Asthma is the leading cause of chronic illness in children, accounting for 14 million missed school days annually. It is the third-ranking cause of hospitalization among children under age 15.

Asthma affects as many as 10–12 percent of children in the United States and the number has been steadily increasing. Since 1980, asthma has increased by 160 percent among children at least four years of age. Asthma is becoming more frequent, and—despite modern drug treatments—it is more severe than in the past. Some experts suggest this is due to increased exposure to allergens such as dust, air pollution, second-hand smoke, and industrial components.

Asthma can begin at any age, but most children experience their first symptoms by the time they are five years old. Boys have a higher incidence of asthma than girls, and the disease is more prevalent in African American children. Children living in inner cities, low-income populations, and minorities have disproportionately higher morbidity and mortality due to asthma.

Causes

About 80 percent of childhood asthma cases are caused by allergies. In most cases, inhaling an allergen sets off the chain of biochemical and tissue changes leading to airway inflammation, bronchoconstriction, and wheezing characteristic of asthma. Because avoiding (or at least minimizing) exposure is the most effective way of treating asthma, it is vital to identify the allergen or irritant that is causing symptoms in a particular child.

Once asthma is present, symptoms can be triggered or made worse if the child also has rhinitis (inflammation of the lining of the nose) or sinusitis. Gastroesophageal reflux disease (GERD), a condition that causes stomach acid to pass back up the esophagus, can worsen asthma. Many pulmonary infections in early childhood, including those due to Chlamydia pneumoniae, Mycoplasma pneumoniae, and respiratory syncytial virus, have been linked with an increased risk for wheezing and asthma. Aspirin and a class of drugs called beta-blockers (often used to treat high blood pressure) can also worsen the symptoms of asthma. Foggy and cloudy environments have been noted to aggravate asthma, and obesity facilitates asthma, but does not cause it.

The most important inhaled allergens and triggers contributing to attacks of asthma are:

• animal dander
• smites in house dust
• fungi (molds) that grow indoors
• mold spores that grow outdoors
• cockroach allergens
• tree, grass, and weed pollen
• occupational exposure to chemicals, fumes, or particles of industrial materials in the air
• strong odors, such as from perfume
• wood smoke

Inhaling tobacco smoke (from secondhand smoke or smoking) can irritate the airways and trigger an asthmatic attack. Air pollutants can have a similar effect.

There are three important factors that regularly produce attacks in certain patients with asthma, and they may sometimes be the sole cause of symptoms. They are:

• humidity and temperature changes, especially inhaling cold air
• exercise (in certain children, asthma is caused simply by exercising, and is called exercise-induced asthma)
• stress, strong emotions, or a high level of anxiety