KEY POINTS:
The worst drink-drivers drink less when there are lower blood and breath alcohol limits, says the country's top traffic officer.
Superintendent Dave Cliff called for the limits to be drastically cut in the Weekend Herald, saying New Zealand was out of step internationally and lower limits would help
reduce the 30 per cent of road deaths caused by drink-drivers.
But feedback to Mr Cliff's proposal was mixed, with many asking how lower limits would stop the worst drink-drivers, such as repeat offender Gordon Armstrong, who killed three motorcyclists and himself last month.
Mr Cliff said the Australian experience showed lowering the blood alcohol limit from 80mg per 100ml of blood to 50mg per 100ml cut the crash rate and resulted in lower levels in those who drank the most.
"The effect appears to be the result of people stopping drinking earlier and not going on to consume more and more alcohol, and thus reach the very high levels that present extreme risk."
Mr Cliff said a lower limit could increase social pressure on repeat offenders.
"If the potential for someone to drink-drive is absolutely scorned, as in it will not be tolerated, that's probably the most powerful preventer we have."
Someone at the present breath limit of 400mcg per litre of breath is thought to be at eight times the risk of having a fatal crash as a sober person. If the limit is lowered to 250mcg, as Mr Cliff is proposing, the risk decreases exponentially, to twice that of a sober person.
A Ministry of Transport report says 14 deaths and 260 injuries could be prevented annually if New Zealand lowered blood alcohol to 50mg - the limit introduced in Australia in the late 1980s. Fifty micrograms is also the upper limit recommended by the World Health Organisation and the standard in many European countries.
Mr Cliff said Australian research on the impact of lowering the limit showed significant reductions in alcohol-related crashes at all blood alcohol levels.
"The research is compelling," he said. "This will work [in New Zealand] and the evidence clearly shows that."
A 1997 study showed crashes decreased 8 per cent in New South Wales and 18 per cent in Queensland.
An earlier study in Queensland also showed an 8 per cent reduction in crashes involving drivers with blood alcohol between 80mg and 150mg, and a 12 per cent reduction in crashes involving drivers above 150mg.
Mr Cliff wants "virtual zero alcohol" of 10mg for drivers aged under 20. The current limit is 30mg. He said recent research had not been conducted on the impact of a 50mg limit because the benefits were accepted.
"It's just an absolute no-brainer. Most progressive countries have already made that move. The Australians are well ahead of us in terms of their understanding of the links between even moderate amounts of alcohol and crash risk."
Experts agree that to reach the limit people have to drink a significant amount and their ability to drive and assess how capable they are of driving is impaired. Police say they often stop drivers who blow below 400mcg but are too drunk to drive.
In New Zealand, readings between 250mcg and 400mcg account for 5 per cent of alcohol-related fatalities, but the figure is considered conservative because police can't order an evidential blood test for uninjured drivers in that range so the figure includes only drivers hospitalised or killed.
The Government has rejected proposals to lower the limits, despite acknowledging there are still more than 100 fatal crashes involving alcohol each year.
But, following Mr Cliff's proposal, Transport Safety Minister Harry Duynhoven and representatives of the other major political parties said they were open to further discussion on the issue.
