September 7, 2009
Secondhand smoke levels higher in cars than in bars or restaurants
The concentrations of secondhand smoke are significantly higher in cars than concentrations generally measured in bars, restaurants and other public places that allow smoking, according to a study by researchers at the Johns Hopkins Bloomberg School of Public Health.
The study is among the first to measure smoking in cars under real-world driving conditions and was published online Aug. 24, ahead of print, in Tobacco Control.
For the study, researchers monitored the air in the cars of 17 smokers and five nonsmokers. “Two air monitors were placed in each car for a 24-hour period,” said study author Miranda Jones, a master’s student at the Bloomberg School, who conducted the study as part of her Diversity Summer Internship Program.
The cars were driven as the participants commuted to and from work for at least 30 minutes. The median air concentrations measured were 9.6 µg/m3 (micrograms per cubic meter). After one to three cigarettes, airborne concentrations of nicotine were 72 times higher than in smoke-free cars. After adjusting for factors such as air conditioner use, vehicle size, window opening and sampling time, there was a 1.96-fold increase in air nicotine concentrations per cigarette smoked.
Study participants also were surveyed on their knowledge of and attitudes regarding health risks of secondhand smoking and relevant regulations/legislation.
“Fifty-three percent of the smokers surveyed said that being unable to smoke in the car would help them to quit smoking altogether,” Jones said.
Ninety-three percent of smokers agreed that motor vehicles should be smoke-free on a voluntary basis, but only 7 percent of smokers agreed that vehicles should be smoke-free by regulation. All of the study’s participants–smokers and nonsmokers–agreed that smoking in the car posed a health risk to passengers.
“Involuntary exposure to secondhand smoke accounts for thousands of cases of respiratory, cardiovascular and cancer deaths in the U.S. every year,” said study author Ana Navas-Acien, assistant professor in the Bloomberg School’s Department of Environmental Health Sciences and the Institute for Global Tobacco Control. “While some states have smoke-free regulations, the high air nicotine concentrations measured in this study support the urgent need for smoke-free education campaigns and legislative measures banning smoking in motor vehicles when passengers, especially children, are present,” she said.
Co-author Patrick Breysse, professor in the Bloomberg School’s Department of Environmental Health Sciences, said, “There is no known safe level of exposure to secondhand smoke. Because smoking in cars can contaminate the entire vehicle, exposure to hazardous components of secondhand smoke can occur long after smoking has stopped,” he said.
Jie Yuan also contributed to the study. The research was funded by a Clinical Investigator Award from the Flight Attendant Medical Research Institute.