By: Rachael Rettner, Senior Writer
Published: 08/08/2013 08:00 AM EDT on LiveScience
More than half of U.S. children with asthma are exposed to secondhand smoke, even though the substance is particularly harmful for kids with the condition, according to a new report.
Between 2007 and 2010, 54 percent of U.S. children ages 3 to 19 were exposed to secondhand smoke, according to the report from the Centers for Disease Control and Prevention. That percentage has changed little over the last decade, the report said.
But there is some good news: the percentage of U.S. children without asthma exposed to secondhand smoke has decreased over the last 10 years, from 57 percent in 1999, to 44 percent in 2010, the report said.
Exposure to secondhand smoke is known to increase children's risk of developing asthma. Secondhand smoke exposure can also make symptoms worse for those who already have asthma. [See 9 Weirdest Allergies]
For children in this study, the report cannot determine which came first: asthma development, or exposure to secondhand smoke, said study researcher Kenneth Quinto, an epidemiology researcher at the CDC's National Center for Health Statistics.
The researchers analyzed children’s blood samples, looking for cotinine, a breakdown product of nicotine that is used as a marker for secondhand smoke exposure. They could not determine where children were exposed to secondhand smoke (whether it was in the home, or a public place), but studies suggest children are more often exposed to secondhand smoke in the home, Quinto said.
Children with asthma are “an especially vulnerable population that we need to protect going forward,” Quinto said.