In a new study the risks associated with secondhand smoke in cars carrying kids was analyzed.
The authors first looked at the mixture of chemicals that make up second-hand smoke and its concentration in cars under different conditions such as volume, speed and ventilation.
Second, they looked at how long a person would be in the car. Third, they observed how long a person would be exposed to the second-hand smoke.
Fourth, the extent of difference between how second-hand smoke affects children compared to adults was added to the risk equation and finally, the authors looked at the health impact, which is hard to determine because of all the different chemicals and toxins a person is exposed to in their lifetime.
"The evidence does not show an absolute risk threshold because a range of environmental, biological and social factors contribute to the risk equation. The evidence does, however, show conditional truths, and the careful enunciation of each contributory condition is the task of public health science," wrote Ray Pawson, School of Sociology and Social Policy, University of Leeds, with coauthors.
"Policy based on science and evidence has to exist amid uncertainty and this is managed by acknowledging the contingencies.
"Thus, i) because of the confirmed cabin space, and ii) under the worst ventilation conditions, and iii) in terms of peak contamination, the evidence permits us to say that smoking in cars generates fine particulate concentrations that are, iv) very rarely experienced in the realm of air-quality studies, and that will thus constitute a significant health risk because, v) exposure to smoking in cars is still commonplace , and vi) children are particularly susceptible and vii) are open to further contamination if their parents are smokers," wrote the authors.
The findings were reported in the Canadian Medical Association Journal.