In Australia, drivers are required to maintain a blood alcohol concentration (BAC) of under 0.05% (i.e. 0.05 grams of alcohol per 100 mL of blood).
However, other countries such as the United States, Singapore, Canada and England have a blood alcohol limit is 0.08. Some have even higher limits, including the Cayman Islands where the limit is 0.10!
Conversely, countries such as Indonesia, Iran and Hungary impose a zero blood alcohol limit for all drivers regardless of experience, and being caught with even the slightest amount of alcohol in your system can result in heavy penalties.
Some argue that the current regime of sending people to court to face a criminal conviction for low range drink driving is too harsh, calling for the limit to be that increased to 0.08.
The Science Behind Drink Driving
Local Court Magistrates often denounce drink drivers by telling them that ‘any amount of alcohol has a negative impact on driving.’
But what does the science say about drink driving – and are there more road accidents in countries which impose higher BAC limits?
A number of studies have evaluated the relative risks of drink driving, with astounding results.
One U.S. study, conducted in 2000, found that the likelihood of being involved in a collision increased exponentially with the driver’s BAC.
It found that a BAC of between 0.02 and 0.049 increased the risk threefold, while a BAC of 0.05 and 0.079 multiplied the risk by 7. Young males aged between 16 and 20 were most at risk.
The results of the study are reflected in the following table:
BAC Multiplies the chances of being killed in a single vehicle crash by:
|BAC||Multiplies the chances of being killed in a single vehicle crash by:|
|For Males||For Females|
|0.02 – 0.049||5 times||3 times||3 times||3 times||3 times||3 times|
|0.05 – 0.079||17 times||7 times||6 times||7 times||7 times||6 times|
|0.08 – 0.99||52 times||13 times||11 times||15 times||13 times||11 times|
|0.10 – 0.149||241 times||37 times||29 times||43 times||37 times||29 times|
|0.150+||15,560 times||572 times||382 times||738 times||572 times||382 times|
As to whether a higher BAC limit means more road fatalities, a comparison of fatal road crashes in the United States and Australia showed that in 2013, there were 10.3 road deaths per 100,000 people in the US, while in Australia the figure was 5.16; suggesting that a lower BAC limit does reduce road fatalities.
DrinkWise Australia points out that a BAC of between 0.05 and 0.08 reduces a person’s ability to judge distances, impairs sensitivity to red lights, results in slower reactions, and shortens concentration.
DrinkWise found that those with a BAC of between 0.08 and 0.12 tended to overestimate their driving abilities, experience euphoria, suffer impaired peripheral vision and displayed impaired perception of obstacles.
Is a Lower BAC Limit the Key?
Rather than increasing our BAC limit in line with other Westernised countries, researchers suggest that road fatalities could be further reduced by imposing an even lower BAC of 0.02. If accepted, the proposal would be the first change to Australian BAC limits in over 30 years.
In 2014, researchers at the Monash University Research Centre compared different countries to see how closely BAC limits were linked to road fatalities, with head researcher Professor Max Cameron concluding that a lower BAC may discourage frequent drinkers from drinking and driving. The researchers recommended a reduction in the BAC limit to 0.02. That recommendation was backed by the European Transport Safety Council in 2012 when it advised all European nations to impose zero BAC limits.
Supporters of a reduced BAC claim that lowering the limit will deter drink driving across the board. According to one news article, there was a 34% reduction in drivers caught with a BAC of between 0.15 and 0.20 and a 58% reduction in drivers with a BAC of over 0.20 when the ACT reduced its limit from 0.08 to 0.05. Such results were replicated in Ireland.
But the government does not look set to change our BAC limits any time soon – the Victorian government rejected the 2014 proposal, and most Australians are in favour of retaining our current limits.