A law in the UK banning smoking in cars carrying children has been associated with a reduction in secondhand smoke exposure among teens, a new study suggests.
England banned smoking in vehicles carrying kids in 2015, and Scotland followed suit in 2016, researchers note in Thorax. To assess how the first smoking ban impacted secondhand smoke exposure, they examined survey data collected in 2012, 2014 and 2016 from 15,318 teens in England and 822 in Scotland.
During the study period, the proportion of youth ages 13 to 15 who reported being exposed to secondhand smoke in cars dropped from 6.3% to 1.6% in England and from 3.4% to 1.3% in Scotland, the study found. The ban in England was associated with a 72% reduction in exposure to tobacco smoke among teens in this age group.
The much bigger drop in secondhand smoke exposure in England, where the ban took effect during the study period, suggests that the law likely played a role, said lead study author Anthony Laverty of Imperial College London.
“Smoking exposes children to air pollutants and chemicals such as tar, arsenic and formaldehyde,” Laverty said by email.
It can cause a range of childhood health problems and is associated with an increased risk of sudden infant death, asthma and lower respiratory tract infections, Laverty said. The risks associated with secondhand smoke exposure can be worse inside cars because pollutants are concentrated in a small enclosed place.
“We know that children with a parent who smokes will be more likely to be exposed to secondhand smoke, which put them at increased risk for infections and other potentially serious diseases,” Laverty said. “We also know that they will be more likely to take up smoking themselves.”
The study focused on young teens who could respond to their own survey questions instead of having a parent provide answers on their behalf. Children were asked how often, over the past year, they had traveled in a car with an adult who smoked during the journey.
Girls and young people from lower-income communities were more likely to report secondhand smoke exposure in cars, the study also found.
The study can’t prove whether or how the ban might have directly affected smoke exposure in cars. It also didn’t evaluate health outcomes.
“Secondhand smoke is the air pollution created by smoking cigarettes during the 90% of the time that the cigarette is not being smoked,” said Jodi Prochaska, a researcher at Stanford University in California who wasn’t involved in the study. It contains “more than 7,000 chemicals, including approximately 70 known cancer-causing agents such as formaldehyde, benzene, vinyl chloride, arsenic, ammonia and hydrogen cyanide,” she noted.
Even though nonsmokers receive a much lower total dose of these chemicals than the smoker, the effects on blood vessels, blood and the heart are surprisingly large, she added.
Smoking in a vehicle with the windows closed can also generate more than 100 times the EPA’s 24-hour recommended exposure limit to particles that irritate the respiratory system and can seep from the lungs into the bloodstream, Prochaska said.
“Smoking by parents causes respiratory symptoms and slows lung growth in their children,” Prochaska, who has consulted for drug and technology companies on smoking cessation treatments, said by email.
“The scientific evidence indicates that there is no risk-free level of exposure to secondhand smoke,” Prochaska said. “Only eliminating smoking in indoor spaces fully protects nonsmokers from exposure to secondhand smoke - ventilation systems do not eliminate exposures.”