Why is asthma so common?

Asthma is very common, affecting approximately one of
every ten Americans at some point in their life, according
to 2001 data from the CDC’s National Health Interview
Survey. It is not clear why asthma has become such a
prevalent, chronic condition. One theory holds that physicians
have become more adept at diagnosing asthma
correctly so that the more precise identification and more
accurate counting of persons with asthma has led to a
perceived increase in diagnosed cases of asthma. Unfortunately,
the opposite is true—the diagnosis of asthma is
too often overlooked, particularly in older age groups and
in adolescents, especially in teenage girls. The fact is that
asthma has truly become more common. A more likely
theory implicates various environmental factors. Smoking,
for example, became socially acceptable for women
after World War II. Infants of mothers who smoke are at
risk for the development of wheezing and asthma in
childhood. Increasing air pollutants and small particles
found in urban or industrial areas may also play an important
role.  From the perspective
of an asthma specialist, the greater awareness of the
importance of air quality in general and the enactment of
laws banning smoking in all indoor public places, such as
in New York City, in particular are a crucial step toward
improving air quality for all.