Who Gets Asthma?

Asthma affects 17.3 million people in the United States (more than 6% of the United States population) and 130 million people worldwide. The number of people affected is eight to 10 times higher in industrialized countries than in developing ones.

Children age 10 and younger account for 50% of asthma cases. In most children, asthma develops before they are 5 years of age, and in more than half, asthma develops before they are 3 years of age.

More than twice as many boys than girls have asthma, although boys are more likely to experience a decrease in symptoms as they reach adolescence. In adult-onset asthma, the number is reversed. Twice as many women than men visit the emergency department and are admitted to the hospital with asthma.

Asthma affects all races worldwide but is more common in blacks and Hispanics, but this may be due to socioeconomic conditions rather than genetics.

Occupational asthma (asthma triggered at work by exposure to irritants present at the workplace) is most common in those who work with animals or animal-derived products and in industries such as plastics, rubber, chemical, textile, electronics, painting, printing, metalworking, baking, and gardening.

Risk factors for asthma include the following:

• Smoking or living with a smoker is a major risk factor. About 25% of children who have asthma have at least one parent who smokes.



• A family history of asthma: If one parent has asthma, a person has a 25% chance of developing it. If both parents have it, a person has a 50% chance of manifesting asthma.



• Having allergies, including hay fever and eczema: It is not known why some people have allergies and some don't, but allergies can be inherited (although people don't necessarily develop the same allergies as their parents have).



• Having allergies or severe viral infections before the age of 3



• Living in the inner city, especially in a low-income group



• Being exposed to mice and cockroach waste products



• Frequently being exposed to triggers