The BMA are at it again. By leveraging (Dr No has been reading too many financial reports of late) proper indignation at unspeakable parents who use their cars as smoke-houses to kipper their kids, they now propose a ban on all smoking in any car – even when the smoker is the only occupant. Perhaps they even want to ban smoking in cars when there is no one in the car. Bloggers and commenters too numerous to mention have pointed out the libertarian and practical legal objections to a total ban – but what about the science behind their proposal? Their briefing paper carries the mark of the BMA Board of Science on its front cover – so the science had better be good. But is it?
The bold headline figure in much of today’s coverage of the ban was that smoking in cars exposed those inside to a staggering twenty three times more toxins than the levels found in a smoky bar. The BMA press release noted coolly:
“Research compiled by the BMA shows that there is strong evidence that smoking in vehicles exposes non-smokers to very high levels of second-hand smoke. This is because of the restrictive internal environment in motor vehicles which exposes drivers and passengers to 23 times more toxins than a smoky bar”
while the briefing paper itself said:
“…studies demonstrate that the concentration of toxins in a smoke-filled vehicle is 23 times greater than that of a smoky bar, even under realistic ventilation conditions”
and tacked on three references. Realistic ventilation, it added in a footnote, “is described as driving at average roads speeds with all four windows completely open” – which sounds more than a little hazardous in itself. But then, that is the BMA for you.
Now, a figure of ‘23 times’ suggests a degree of scientific precision, so Dr No decided to check the references where he could. As it happens, all three are available: here, here and here.
All too soon (this was quickly becoming a familiar story), the evidence started to thin and then disappear like smoke rings blown in a breeze. Strands of the all too common incestuous Chinese whispers started to appear, as one source quoted another in a merry-go-round of mutual support. And then came the crucial evidence for ‘twenty three times more toxins than a smoky bar’ – but it went up in smoke – in an Irish pub (ref 1, page 14):
“To provide some context about the PM 2.5 levels recorded in this study, in a recent report of PM 2.5 levels in Irish pubs throughout the world, the average level of PM 2.5 in 48 Irish pubs that allowed smoking was 340 μg/m3. In Condition 1 (motionless car with all windows closed), the average level during cigarette smoking (M = 3,850.9 μg/m3, range = 1,696.8 to 7654.7 μg/m3) was over 11 times the level of an Irish pub in which smoking was allowed.”
A motionless car with all windows closed…but still nowhere near twenty-three times the ‘smoky bar’…just eleven times…
And then Dr No came across this. Produced by a couple of anti-smoking campaigners from Australia only last year (and so more recent than the three references the BMA rely on for the ‘twenty-three times’ figure), it thoroughly debunks the ‘twenty-three times’ myth. No need for Dr No to rehearse the argument – it had already been done – by anti-smoking people.
Unsurprisingly, the BMA briefing paper makes no mention of this inconvenient paper. Perhaps the BMA knew of it, but suppressed it. Or perhaps they never even came across it, which is a pity, because it contains a pithy and pertinent observation:
“The biggest danger of inaccurately interpreting research on smoking in cars for the sake of a snappy media sound bite is to lose favour with an overwhelmingly supportive public and to provide ammunition for opponents of tobacco control.”
Board of Science? More Board of Myth. Dr No is left gasping…
It seems that the BMA have now ‘spotted’ that their 23 times claim was baloney, and have now ‘adjusted‘ their press release, and added a coy footnote:
“This is a change in wording from the original press release following an error that was found in the briefing paper shortly after publication.”
This really is not good enough. These clowns call themselves the ‘Board of Science’ yet are incapable of conducting a basic review of the literature, and go public with ‘factoids’ plucked from thin air. Windy Viv is still available here on the Today programme, puffing the 23 times figure for posterity. Perhaps it is time at last time to rename the programme ‘Yesterday’. The rest of the media (if you care to google the matter), on the other hand, are all over the place: some are still hooked on ’23 times’, while others have realised the BMA have been caught out doing smoke and mirrors.
Dr No is not even impressed by the eleven times figure. The ‘Condition 1’ Dr No quoted (he didn’t feel ready then to knock too many nails in the BMA coffin) in the original post is in fact the most extreme condition, akin to locking oneself in a biscuit tin with a Hamlet six-pack.
If we consider all the conditions, which include more normal scenarios, the 11 times figure starts going up in smoke too. The full paragraph in the paper reads:
“To provide some context about the PM 2.5 levels recorded in this study, in a recent report of PM 2.5 levels in Irish pubs throughout the world, the average level of PM 2.5 in 48 Irish pubs that allowed smoking was 340 μg/m3. In Condition 1 (motionless car with all windows closed), the average level during cigarette smoking (M = 3,850.9 μg/m3, range = 1,696.8 to 7654.7 μg/m3) was over 11 times the level of an Irish pub in which smoking was allowed. At the other extreme, in Condition 3 (all windows open all the way while driving), the PM 2.5 level was the lowest (M = 60.4 μg/m3, range = 15.7 to 220.5 μg/m3). In Condition 2 (all windows closed), the average level was about 7 times higher than the average Irish pub (M = 2,412.5 μg/m3, range 760.6–6156.6 μg/m3). In Condition 5 (air conditioning), the average level (M = 844.4 μg/m3, range = 202.0 to 2,504.5 μg/m3) was almost 2.5 times higher than the average Irish pub. In Condition 4 (holding the cigarette outside the half-open driver’s window), the average level (M = 222.5 μg/m3, range = 66.7 to 960.0 μg/m3) was slightly lower than the levels of the average Irish pub in countries where smoking was allowed in bars/pubs.”
In condition 4 (which is not that usual a way to smoke in a car), levels were actually slightly lower than in a pub….
Bob – the BMA doesn’t get any money from Dr No either. He prefers to spend the money on Capsatns Full Strength and Pusser’s rum.
The BMA are supposed to be the doctors’ Trade Union, but this wrwtched ‘Board of Science’ seems to operate in a silo, coming out with their nannying nonsense. At a time when the future of the NHS is threatened by Lansley’s Health and Social Care Bill, and other unions are threatening strike action over pensions, the BMA once again look like a useless bunch of to**ers, who really ought to have something better to do with their time.
DOI: I am a doctor, but I am not a BMA member, and this sort of thing is the reason why I decline to give them my money. (And no, I don’t think we should strike over pensions or anything else, but it would be nice if the BMA concentrated on their role as a trade union and stopped preaching).
dr no
have you seen dr rant and dr grumble have gone offline?
strange
Dr No has. He also couldn’t help noticing Dr G’s last post was called ‘It’s Over’, and was posted of Guy Fawkes’ Day, and the chief content was a video to do with Hitler.
Dr G’s last post is still (for the time being) in google’s cache here. In it, Dr G does make a comment, in reply to one by JD, that may or may not be part of the full story.
Curious coincidence too that Carol Black should be back in the news again today…
http://ferretfancier.blogspot.com/2011/11/gmc-social-media-and-our-lives.html
Este blog é uma representação exata de competências. Eu gosto da sua recomendação. Um grande conceito que reflete os pensamentos do escritor. Consultoria RH
I am someone who personally hates smoking and I agree to the facts that are given in the article of the smoking in the car and the problems that are caused following the main cause. This is really a matter to discuss that this causes much impact on the human body.
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