Asthma is a growing epidemic in the U.S. Currently 6.8 million kids have been diagnosed with the condition, a number that experts at the Centers for Disease Control and Prevention think will only continue to rise. It has long been thought that urban living was one of the primary risk factors for developing asthma, but a new study has debunked the theory of the "inner-city asthma epidemic," leaving experts to wonder what really is to blame for the rise in asthma cases.
In the 1960s, health experts started looking more closely at the causes and demographics of asthma in this country. They noticed that big cities had higher rates of hospitalization and emergency room visits for asthma. So broad assumptions were made about city living and its link to the development of asthma.

But in a new study, Dr. Corrine Keet, a pediatric allergist at the Johns Hopkins Children's Center in Baltimore, decided to test this assumption to see if urban dwelling children really were more likely to develop asthma than their suburban or rural living peers. Her findings debunked a theory that has guided asthma care and prevention for decades. The study, which was published in the Journal of Allergy and Clinical Immunology, found that inner-city living was actually not as big of a risk factor for asthma as previously thought.

Sure, kids who live in cities have high rates of asthma. But according to Keet, "We also found that even more children had asthma in some poor suburban and medium-sized towns in other regions of the country." In addition, she added, for children outside of the Northeastern states, "living in the inner city didn't seem to be a risk factor at all for having asthma."

To crunch the numbers, Keet and her team used national survey data on more than 23,000 children aged 6 to 17 between 2009-2011. They evaluated asthma rates based on population data as well as factors such as income, race and ethnicity. After adjusting for those other factors, they found that statistically, there was no real difference between asthma rates for city kids and those who lived in other communities.

So if city dwelling is not a factor for childhood asthma, what is? According to the data, being poor, black or Puerto Rican were the most important factors that determine a child's asthma risk. Black and Puerto Rican children had much higher rates of asthma — 17 and 20 percent, respectively — than white children (10 percent), Hispanic children (9 percent) and Asian children (8 percent).

When it came to geography, there were big differences in asthma rates between kids living in the Northeastern cities (17 percent) and those who lived in western cities (8 percent).

So it's more likely that poverty may be a bigger risk factor for asthma than city living. And there could be a number of reasons for that. Low-income housing is more likely to have mold and cockroaches — two factors known to contribute to asthma. Also, smoking rates are higher in poorer communities and secondhand smoke exposure is another risk factor for asthma. Finally, children living in low-income households are more likely to feel stressed and that can affect their immune systems' ability to respond to threats.

Hopefully, this study will serve as a launching point for additional research that helps health experts zero in on the real causes of asthma, and the best ways that parents and health care providers can prevent it.

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