Doctors’ calls to cut drink-driving limits in much of the UK are welcome but must be matched by enforcement to improve road safety, experts have said.
On Tuesday the British Medical Association (BMA) passed a motion calling for the drink-driving limit in England, Wales and Northern Ireland to be cut from 80mg per 100 millilitres of blood, or 35 micrograms per 100 millilitres of breath, to lower levels seen in many other countries including Scotland.
An independent review before the change in Scotland included evidence that drivers with a blood alcohol concentration between 50mg and 80mg were six times more likely to die in a road traffic accident than those with zero blood alcohol.
Colin Angus, a senior research fellow with the Sheffield Alcohol Research Group at the University of Sheffield, said the BMA’s call to lower the current drink-drive limit was sensible and proportionate.
“The current 80mg/100ml threshold is one of the highest in the world, at odds with most other developed nations, and higher than WHO’s recommended level of 50mg/100ml (and 20mg/100ml for new drivers). The evidence is clear that higher drink-drive limits lead to more accidents, and it’s important to remember that many of these accidents involve more people than just the drink-driver themselves,” he said.
However, research also suggests other factors may be important.
In 2014 the limit in Scotland was reduced to 50mg/100ml, but when experts investigated the impact of the shift, they found no significant drop in road traffic accidents, even when looking at accidents known to have involved alcohol.
“We don’t find an impact on drink-driving, on accidents, fatal accidents, serious or slight accidents,” said Dr Jonathan James of the University of Bath, who co-authored the 2021 study.
James added the team looked at myriad factors, including the time of day, availability of public transport and whether the setting was urban or rural, but still found no effect.
That, the team suggest, was down to two factors: the reduction in the drink-drive limit was not associated with a rise in alternative transport options, and there was no increase in enforcement, such as police numbers or breath testing.
“If you look at the international evidence, it’s very much that where the change in the law has worked, it’s either enforced or whether there’s been a change in the enforcement alongside,” said James.
However, James said he supported the BMA’s call. “It could well be the case that if you change the law in England, if you then also enforce or have more resources to enforce the law, that could lead to a reduction in road traffic collisions and alcohol-related road traffic collisions in particular,” he said.
Angus also stressed the importance of enforcement. “In the UK, police forces don’t have the power to undertake random breath tests – police need to have a suspicion that the driver is under the influence in order to test them – which goes against WHO recommendations, and there are reasons to believe that breath test numbers overall have fallen,” he said. “If it’s a choice between lowering the limit, or not, alongside no change in enforcement, then it would still be better to lower the limit, but if we want to have the biggest impact on road safety then we need both.”
But just what “sticking to the limit” looks like, in terms of pints or units, is far from clear. As John Scruby of Campaign Against Drink Driving points out, it differs from person to person, while a rise in alcohol content of drinks has also caused confusion.
“People still think that they can have two drinks and drive or they can have two units and drive. But that’s not the case; it never has been the case,” said Scruby, adding that many people were unaware what the legal limit meant.
Scruby added that even for a given individual, alcohol levels in the body could vary after drinking. “It all depends on how much you’ve had to eat, how much you’ve slept, how much exercise you’ve had. There’s so many factors that go into it,” he said.
Research published in December 2021 revealed as many as half of participants who thought they had reached the drink-driving limit when consuming alcohol had, in fact, already passed it.
Scruby said the message was: don’t mix alcohol and driving. “That’s the only way you could be sure to be under the drink-drive limit. That’s the only way you can be safe to drive,” he said.
A Drinkaware spokesperson said: “Even small amounts of alcohol can affect your ability to drive and there is no reliable way to drink and stay within the limit. If you need to drive, there are lots of non-alcoholic alternatives available.”
