Second-hand smoke can be 27 times more toxic in a car than a smoker's home, it says in a report published today.
The report in question comes from the UK Faculty of Public Health, which says:
In a closed car, levels of second-hand smoke can be extremely high – the concentration in cars can be up to 60 times higher than in a smoke-free home, and up to 27 times greater than in a smoker’s home.
60 times smokier than a house with no smoke in it? Don't ask me, I've given up trying to figure out their logic. Presumably it has something to do with measuring nanograms of some biomarker—not what you or I would call 'smoke'.
But let's ignore that, and let's ignore fact that people very rarely smoke in a "closed car". The main point, as Dick Puddlecote has pointed out, is that this "27 times greater" myth has been thoroughly debunked. Or rather, the "23 times greater" myth, as it seems to have been further embellished since I discussed it back in March, when I traced it back to an obscure article in that prestigious scientific journal Rocky Mountain News.
Two months later, the Canadian Medical Association Journal published an article by Becky Freeman and Ross MacKenzie which not only concluded that the figure had no basis in fact, but actively encouraged fellow anti-smoking campaigners not to use it.
We recommend that researchers and organizations stop using the 23 times more toxic factoid because there appears to be no evidence for it in the scientific literature.
The CMAJ article is behind a pay-wall, but it tells the story with this graph (click to enlarge). [UPDATE: You can read it here.]
This little tale of Chinese whispers does not just involve local newspapers not bothering to check their facts. After the "23 times" claim appeared in Rocky Mountain News, it was used in a Tobacco Control editorial and then mentioned in Nicotine and Tobacco Research. From there, it spread to the Ontario Medical Association and the British Columbia Ministry of Health.
By 2009, it had gone global. The Australian Medical Association, Action on Smoking and Health (Ireland), the European Lung Foundation and Action on Smoking and Health (England) were all taken in. The Sunday Times, the Irish Times and the Irish Medical Times quoted the figure. And they were not alone. Take this, for example, from the Irish Independent :
Dr Angie Brown, chairwoman of ASH Ireland, said the ban has been already introduced in several regions in Australia and the United States, while it is being considered in the Netherlands and South Africa. "There is irrefutable evidence to show that a car can be 23 times more toxic than a home environment in the context of passive smoke," she warned.
When the Royal College of Physicians campaigned for a total ban on smoking in cars in March 2010, they insisted that levels in cars were "20 times higher" than in smoky bars—a claim that fails the basic test of believability.
All of this based on an indirect quote that once appeared in a now defunct Denver newspaper.
And, despite being comprehensively and explicitly exposed as a myth in a major medical journal, here it is again, still unreferenced in a public health report and now exaggerated still further. And still, of course, appearing in national newspapers to sway public opinion.
All of which means that (a) the UK Faculty of Public Health has carried out some new research which it's keeping very quiet, (b) they don't keep in touch with what's being written in the medical journals, even when it's written by prominent tobacco control figures like Becky Freeman, or (c) they don't care about getting their facts right.
As it says in the CMAJ paper:
Unfortunately, inaccurate reporting of health information is not an uncommon phenomenon.
To put it mildly.