Exposure to smoke in cars may worsen asthma: study

People with asthma may face increased risk from secondhand smoke exposure while riding in the close quarters of a vehicle, according to U.S. researchers.

In a survey covering four southern states, people exposed to secondhand smoke in vehicles were twice as likely to have asthma compared to those who were not exposed.

The study team cannot prove the smoke exposure caused asthma in the people interviewed, but they warn that smoke can seriously aggravate asthma symptoms and suggest drivers and passengers voluntarily ban smoking in their cars.

“It’s problematic from a public health perspective,” said Brian King, an epidemiologist with the Centers for Disease Control and Prevention in Atlanta and a co-author of the study. “Secondhand smoke is a lethal cocktail of carcinogens and toxins. You have a dangerous exposure in a very confined environment.”

Asthma is a chronic disorder of the lungs and airways that causes them to swell, an inflammatory response that can be fatal. In 2007, asthma was linked to more than 3,400 U.S. deaths, according to the American Academy of Allergy, Asthma and Immunology. About 25 million Americans have been diagnosed with the condition.

King and his coauthor analyzed the responses from a phone survey of 18,000 non-smoking adults living in Indiana, Kentucky, Louisiana or Mississippi. They found that 7.4 percent reported having asthma, and 12.4 percent said they had been exposed to tobacco smoke in a vehicle in the past week.

The people exposed to smoke had twice the odds of also having asthma, the researchers report in the journal Tobacco Control.

The study establishes a link between asthma and secondhand smoke in cars, King said, but that does not mean one causes the other. “We don’t know what came first,” he said. “All we know is that people with asthma are exposed. It’s not necessarily that the exposure is causing the asthma.”

The survey also found that among the participants with asthma, less than 10 percent of those who established smoke-free rules in their vehicles reported having been exposed to smoke. That compared to 57 percent of people with asthma who did not have smoke-free rules.

Hal Strelnick, a professor of family and social medicine at Albert Einstein College of Medicine in New York City, encourages people with asthma to voice their concerns when in the car with a smoker - even though it may be challenging to speak up.

“(When) someone’s giving you a ride, and they light up a cigarette, the social dynamics are difficult,” Strelnick said. “Even people who have asthma have difficulty telling a smoker to stop smoking in the car.”

Cigarette or cigar smoke in such a confined space can be hazardous to your health and the health of those around you, Strelnick added. If you are a smoker driving non-smokers, ask your passengers for permission before lighting up, or voluntarily give up smoking in your vehicle, he advised.