Fewer workers are being caught on drugs, despite workplace testing becoming more prevalent, latest figures show.
Information from the New Zealand Drug Detection Agency showed 81,410 on-site drug-screening tests were carried out last year, 16 per cent up from the previous year.
But only 5.5 per cent of tests showed the presence of drugs, down from 6.4 per cent in 2013.
An industry breakdown showed construction workers had the highest number of positive results - 14 per cent of almost 11,700 tests.
Raywin Head, group compliance manager at transport and construction company Smith and Davies, said they began drug screening about 15 years ago.
"No one is employed without a pre-employment drug and alcohol test, and then we do random, post-accident ... [tests].
"It's absolutely critical. A big logging truck bowling down the road with someone impaired is not what you want," she said.
Mrs Head, who has been in the transport industry for 35 years, said drug awareness among the workforce had increased dramatically.
"As a responsible company, you can't afford to turn you're back on it anymore, and other companies won't be able to for much longer."
The tourist and adventure activity sector had the highest incidence of cannabis detection, with 71 per cent of tests showing positive results for the drug.
Brendon MacRae of Taupo Tandem Skydiving said his organisation started testing staff 14 years ago.
"Drugs are becoming more readily available to everybody and because of what we do for a job, we decided it was time to do it."
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Both Mr MacRae and Mrs Head said any workers who returned a positive drug test were stood down immediately.
The companies had rehabilitation programmes to help workers overcome drug and alcohol problems and no one was allowed to work unless they proved they were free of the substances, they said.
Cannabis was detected most frequently in "traditional" cannabis growing areas such as Northland, Waikato, Bay of Plenty and the East Cape, the agency figures showed.
Drugs in the workplace
* 2012 Carterton balloon tragedy: 11 people were killed when the balloon caught fire and crashed after hitting power lines. Test results showed the pilot had likely smoked cannabis before the flight. An investigation concluded cannabis impairment could not be excluded as the cause of his errors of judgement
*2010 Fox Glacier skydiving crash: Nine people were killed after the unbalanced and overloaded skydiving plane they were in crashed and burst into flames near the Fox Glacier airstrip. Both pilots had cannabis in their system but a coroner found this would not have contributed to the outcome.