Smoking in the car produces air pollutants that exceed World Health Organisation air quality guidance – and opening windows makes little difference, researchers warn today.
The results of the largest study ever to be undertaken show that children are at increased risk of health problems if they travel in a vehicle while someone is smoking.
It has led to the report authors to backing calls from the Royal College of Physicians Tobacco Advisory Group, which said a ban on smoking in cars would help to reduce the harms associated with exposure to second hand smoke.
Researchers from the Scottish Centre for Indoor Air, led by Dr Sean Semple at the University of Aberdeen, UK, measured levels of fine particulate matter every minute in the rear passenger area during typical car journeys made by smokers and non-smokers over three days.
They made the measurements using an aerosol monitor, which is often used to assess second hand smoke exposure, placed at child head height.
Seventeen drivers were followed, 14 of whom were smokers: five said they smoked 20 or more cigarettes a day; seven smoked between 10 and 19 a day; two smoked fewer than 10.
All drivers made a total of 104 journeys that lasted between five and 70 minutes, with an average duration of 27 minutes.
Particulate matter levels were recorded for 83 journeys, of which 34 were smoke free. It was found that levels were on average 7.4 µg/m3 during non-smoking journeys, but were about 10 times as high (85 µg/m3) on journeys where smoking occurred.
Levels of particulate matter were strongly linked to the numbers of cigarettes smoked, with levels peaking at an average of 385 µg/m3, and once got as high as 880 µg/m3.
Smokers tended to open car windows to provide some ventilation, but levels of particulate matter still exceeded the maximum safe limit recommended by the World Health Organisation of 25 µg/m3 at some point during all car journeys during which somebody smoked.
“Children are likely to be at greater risk from [second hand smoke] exposure due to their faster breathing rates, less developed immune system and their inability to move away from the source in many home and car settings,” say the authors, whose study is published in the latest edition of Tobacco Control.
Several other countries, including Canada, the US, Australia, Cyprus and South Africa have already introduced state or national legislation to ban smoking in cars in which children are passengers.
Second hand smoke in cars: assessing children’s potential exposure during typical journey conditions Tobacco Control October 16 2012; 578-83; doi 10.1136/tobaccocontrol-2011-050197
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