I'm sure many UK readers, like me, woke up to the Today programme last Wednesday morning and heard Dr Vivienne Nathanson from the British Medical Association (BMA) speaking about the association's latest report, which called for a blanket ban on smoking in cars. Meaning that adults would no longer be able to smoke even if they were by themselves in their own private cars.
Dr Nathanson, head of science and ethics at the BMA, was categorical: "The evidence is that, in fact, the levels of toxins that can build up in a car do reach 23 times the levels in a smoky bar."
Pressed on the figure, she was asked, "that is peer reviewed? Everyone in the scientific community accepts that it's true?"
Her response? "Absolutely".
There was no room for doubt. It was a fact. Something every scientist agreed upon. The evidence was peer reviewed. It was Absolutely True. The 23 times claim was then repeated by almost all media outlets, often as the lead story, throughout the day.
Yet, the very next day, the BMA slipped out an apology. This figure of 23 times wasn't Absolutely True after all. The press release stated they had replaced the claim: "Further 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" with: "Further studies demonstrate that the concentration of toxins in a smoke-filled vehicle could be up to 11 times greater than that of a smoky bar."
So, not only had the figure been revised down from 23 times to 11 times, but whereas the 23 times statistic held "even under realistic ventilation conditions", now it was only "up to 11 times", meaning there is the possibility it could be considerably less.
In the press release, the BMA offered no explanation for the dramatic lowering of the figure, instead simply saying "we apologise for this error". Ben Goldacre points to some of the possible reasons in a blog post remarking, "if it is as they say - and it looks pretty damning - then this report from the BMA is pretty shifty".
The only thing that has been more staggering than the BMA's retraction is the lack of media coverage reporting the change. Which means that, unless they scour the BMA's not-so-easy to navigate website, the tens of millions of people who are likely to have heard the dodgy 23 times stat being repeated ad infinitum on Wednesday will currently be none the wiser that it is not Absolutely True.
Some have seriously questioned whether even the revised 11 times statistic is correct. Not that many of the arguments that Dr Nathanson made on the Today programme would really be affected by the revised figures. Because, once the very reasonable argument was put to her that it should be up to adults to decide whether or not they drive in a smoky car or not - "If it's just an individual who likes smoking and understands the risks, that's a different sort of effort isn't it?" - she rapidly changed tack.
To try to get around this tricky business of adults being allowed to make up their own minds whether they smoke in their own cars or not, she first started claiming that "not only are they harming themselves, but there is a distraction risk that is recognised in the highway code and has been for some time".
But is it really within the BMA's remit to start talking about how smoking can lead to greater road accidents? If it really was such a problem, then surely it's something the Department for Transport or the police should be raising?
She then went on to argue that the reason she wants to ban it in cars, rather than in someone's sitting room, is because people have less choice about whether they travel in the car of a smoker than whether they visit a smoker's home. A dubious claim that she didn't back up with statistics. She then said that "vulnerable and disabled adults" and also "people who don't have their own cars" could potentially suffer as they might face a situation where they have to enter into a car where someone was smoking.
So, the argument ceased to become one that was anything to do with health, and instead become one to do with fairness. Some people are vulnerable and some are, perhaps, unable to afford their own cars and so, therefore, smoking must be banned in all cars as a result because they may feel pressure to get into a car with a smoker.
It's quite a stretch of logic isn't it? To propose that anyone who owns a car - regardless of whether they have kids and regardless of whether they allow others to travel as passengers - should be banned from smoking in it because it's possible at some point a "vulnerable" person may get into the car.
Moreover it's one that speaks to a deep misanthropy. Smokers aren't all selfish creatures prioritising their right to puff over everything else. Many I know won't smoke in their car when others are in it; and certainly not when children are there. I'm sure that the BMA's statistics - had they been correct - would lead many of those who did smoke in cars to pause for thought and perhaps stop doing it.
But this doesn't seem to be enough for the Dr Nathanson and the BMA. Their evidence can't just be presented to smokers who can then take it on board and make decisions themselves about whether to smoke in cars accordingly. Nor can non-smokers concerned about their health be relied upon to be able to simply ask the smoker to stop. Instead they are calling for an outright ban preventing smokers from making the decision at all, unless they want to face criminal charges.
When BMA representatives resort to arguments about road safety and fairness in order to override questions of individual choice, something is going seriously wrong. How about rather than getting involved in politics and lobbying the state to rip personal choices away from us, the BMA instead uses its time and resources instead to get its facts straight? Ensuring they are Absolutely True? Based on its reputation-damaging dodgy headline statistic in its smoking in cars report, it would be well advised to do so.
Follow Patrick Hayes on Twitter: www.twitter.com/P_Hayes