In the December 6th edition of The Age an editorial commending smokefree car legislation quoted a 2006 study by the Harvard School of Public Health that “found that cigarette smoke in a car can be up to 10 times more dangerous than it is in a house.” Being both baffled and intrigued by this shocking and nicely rounded statistic, I decided to read the original study. Twice. There was absolutely no mention of increased toxicity – 10 times or otherwise.

Undeterred, I contacted the lead author of the study. Much to his frustration he told me that, “unfortunately this statistic has been doing the rounds since we first got some media coverage with this study. As far as I know it has no empirical basis and is certainly not related to any research we have done.” He suspects that one media outlet misinterpreted the paper and others have since carelessly copied the quote.

Seems this is a common issue in reporting on smoking in cars. While researching a paper on smoking bans in cars I discovered a curious “factoid”. In 2005, a claim by the AMA that “exposure to second-hand smoke in a car was 23 times more toxic than in the home” first appeared in the Australian print media and has since been repeated countless times. This “factoid” was eventually sourced back to a statement made by a Colorado senator to a local newspaper. An exhaustive search of the research literature failed to locate a scientific source for this statistic. (A polite way of saying it is totally made up!) A Google search however shows that globally, many highly respected tobacco control organisations are using this claim in their communications.

Might media outlets and health organisations try to actually read the original research material they are quoting? Second hand quoting is just as harmful as second hand smoke.