DIY breath test device proves risky

A man narrowly avoided a drink-driving charge just minutes after his own DIY breath testing device showed he was under the limit.
The man was pulled over by police in Welcome Bay and told them he was fine because he had just tested himself with a personal alcohol breath tester, which recorded his level as under the legal limit of 400 micrograms per litre of breath.
But he blew right to the limit of the police breathalyser - only just avoided a drink-driving charge.
Inspector Kevin Taylor, road policing manager for the Bay of Plenty Police District, would not say what the readings were except that there was a difference of about 35 per cent.
The man should not have driven at all, Mr Taylor said.
"This is hardly a major sacrifice compared with the consequences of a drink-drive conviction, or worse still having a crash and injuring or killing yourself or someone else."
The incident happened last week but has only just been revealed by police.
The breathalyser the man used was available over-the-counter, prompting police concern at the unreliability of such devices.
Breathalysers can be bought for anywhere between $9.99 and $399 online, with some offering warnings they "cannot be used as a legal defence".
"Police have no input into how across the counter devices are calibrated or maintained by owners. Once bought there is no knowing how they are used or looked after," Mr Taylor said.
The devices New Zealand Police use are calibrated and certified as approved devices for breath alcohol testing.
Sobercheck is New Zealand's leading retailer of personal breath testers and specialises in drug and alcohol testing equipment.
While it is not known what brand of tester the man had, Sobercheck manager Gavin Foster said readings from any personal testers should be indicative only.
"Accuracy and personal breathalysers - the two don't go together," Mr Foster said.
He said to compare personal breathalysers to police ones would be "like getting into a Mini and expecting it to perform with racing cars."
Sobercheck breathalysers were some of the most accurate retail devices available in New Zealand but still gave a margin of error of up to 50mcg.
People needed to ensure they regularly calibrated their devices for optimal results, Mr Foster said.
Mr Taylor said if over-the-counter breathalysers were used to see how close a driver was to being over the limit, then they are approaching the issue from entirely the wrong perspective.
"The issue is public and community safety, not 'how much I can drink and still get away with driving'.
"The best and safest alcohol level for driving is zero."
Mr Taylor said police often encountered people who said they thought they were under the limit.
"It is time [people] stopped playing games with each others' lives. So far this year we have lost 18 lives on Bay of Plenty roads as a direct result of drink-driving. That is 18 too many." Bay of Plenty police have caught more than 2300 drink drivers this year.