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Kids' exposure to secondhand smoke drops — except among those with asthma

At a time when many Americans have managed to kick the habit, a surprising new government report finds that asthmatic kids are just as likely to be exposed to secondhand smoke as they were a decade ago, especially if they come from poor families.

There is some good news, though. During the same time period, secondhand smoke exposure dropped significantly among kids who don’t have asthma, according to the report by the National Center for Health Statistics.

“What surprised us was that among kids with asthma, secondhand exposure to smoke did not decrease at all,” said the report’s lead author, Dr. Kenneth B. Quinto, an epidemic intelligence service officer with the Centers for Disease Control and Prevention. “I think we could be doing a better job educating parents with children with asthma about the health effects of secondhand exposure.”

The new findings are “counterintuitive,” said Dr. Sande Okelo, an asthma expert unaffiliated with the new study and an assistant professor of pediatric pulmonology the David Geffen School of Medicine and the Mattel Children’s Hospital, both at the University of California, Los Angeles. “I think this would be very unexpected for your average physician, who would assume that the rates of smoking are going down for everyone.”

The data for the new report came from the ongoing National Health and Nutrition Examination Survey (NHANES), which periodically interviews and examines a large nationally representative sample of Americans.

Quinto and his colleagues looked at health information collected on 12,000 children aged 3 to 19. Along with surveys, the NHANES researchers collected blood samples, which were tested for the presence of serum cotinine, which is a marker for secondhand smoke exposure.

The researchers found that from 1999 to 2010 the percentage of children without asthma who had been exposed to secondhand smoke decreased from 57 to 44 percent , while there was a barely perceptible drop, 58 percent to 54 percent, among kids with asthma.

When the researchers looked only at recent data - from 2007 to 2010 - they found the biggest disparities in secondhand smoke exposure were related to income.

Among families with incomes below 185 percent of federal poverty guidelines, nearly 68 percent of asthmatic kids showed signs of exposure to secondhand smoke, as compared to nearly 59 percent of those without asthma. Among families with incomes between 185 and 350 percent of the poverty line, the numbers were even more striking: 60 percent of kids with asthma showed signs of being exposed to secondhand smoke, as compared to nearly 46 percent of those without asthma. Among families with incomes above 350 percent of the poverty line, there was virtually no difference between kids with asthma and those without: 23 percent versus 25 percent.

The explanation for those findings may be that income can be a proxy for educational level, Quinto said, adding that the more educated parents may better understand how smoking affects asthma.

Quinto said this study didn't look at the role secondhand smoke may have played in causing asthma.

The report also found that non-Hispanic black children had a higher rate of exposure to secondhand smoke, whether they suffered from asthma or not, at 63 percent. Mexican American kids had the lowest rates of secondhand smoke exposure. But again, the rate was higher among those with asthma, 36 percent versus 27 percent.

The new findings fall in line with other research on poor kids and asthma, said Patrick Breysse, a professor in the department of environmental science and co-director of the Center for Childhood Asthma in an Urban Environment at the Johns Hopkins Bloomberg School of Public health.

“I’m not entirely surprised by the results,” Breysse said. “We know that over the last 10 years smoking has been banned in public places. The last bastion of smoking is the home environment.”

Beyond that, studies have found that asthma rates are higher in low income areas of the inner city, and smoking rates are higher in the same areas, so their intersection is not surprising, Breysse said.

The new report makes it clear that “there needs to be a more targeted effort to reach some of these groups that are at risk for ongoing exposure to secondhand smoke,” Okelo said.

Breysse agreed. “I think there has to be a concerted campaign to get the message out to all ethnic groups and all socioeconomic strata.”