Half of drinkers believe they are safe to drive despite exceeding the legal alcohol limit, a new study suggests.
Dr Kai Hensel of the University of Cambridge, who led the research, said the findings indicate the “best advice” for people intending to drive is “just don’t drink”.
Ninety students in Germany were asked to declare when they believed they had reached the country’s drink-drive limit after being given beer or wine.
More than a third (39%) of participants had already exceeded the threshold by the time they came forward on the first day of the study.
This rose to 53% on the second day.
The study was published in Harm Reduction Journal.
As many as one in two people in our study underestimated how drunk they were – and this can have devastating consequencesDr Kai Hensel
Dr Hensel, who also works for Witten/Herdecke University in west Germany, said: “In countries with legal alcohol limits, it’s usually the driver who makes a judgment about how much they’ve drunk and how fit they are to drive.
“But as we’ve shown, we are not always good at making this judgment. As many as one in two people in our study underestimated how drunk they were – and this can have devastating consequences.”
Department for Transport figures show the number of people killed or seriously injured (KSI) in drink-drive crashes on Britain’s roads reached an eight-year high in 2019.
There were about 2,050 KSI casualties in collisions where at least one driver was over the alcohol limit, an 8% increase on the previous year and is the highest level since 2011.
The researchers in Germany noticed that participants became poorer at estimating their breath alcohol concentration the drunker they became.
Dr Hensel warned that this could have “serious consequences” in countries with higher legal driving limits.
The limit in England, Wales and Northern Ireland is 80mg of alcohol per 100ml of blood, while no other part of Europe has a limit above 50mg/100ml.
In 2014, the Scottish Government reduced the limit to 50mg/100ml.
Dr Hensel said: “A significant number of people might misjudge how drunk they are and consider themselves fit to drive when in fact they have a potentially dangerously high level of alcohol in their blood.”
He added: “The best advice is that if you’re driving, just don’t drink.
“But if you really do feel like a drink, then look into your own alcohol tolerance. This differs from one person to the next, depending on your sex, weight and age, and there are some reliable apps out there that can help guide you.”
UK police forces are intensifying enforcement of drink and drug-driving rules in the run up to Christmas, targeting known hot spots.
Some 6,730 motorists were caught during the annual Christmas-time operation in 2020.