A Whanganui forklift driver was exposed to potentially deadly gas during a leak at Tasman Tanning.
The driver lost consciousness twice after being exposed to hydrogen sulphide, and suffered concussion and gashes to the face.
The gas leak at the Whanganui tannery in Heads Rd happened in April last year.
And on Friday, in the Whanganui District Court, Tasman Tanning was fined $380,000 for breaches of safety.
The prosecution was brought by WorkSafe NZ which cited multiple failings by the company, which was also ordered to pay $18,000 in compensation to the forklift driver.
WorkSafe chief inspector Keith Stewart said the investigation into the incident found numerous failings, including a lack of training and warnings, and failure to provide personal gas monitors.
"These failures led to unnecessary and unacceptable injuries to a worker."
He said the dangers of hydrogen sulphide gas were well-known in the tanning industry, and the worker was shifting containers when he was overcome by the gas.
"He fell to the ground, striking the back of his head on the floor.
"He regained consciousness, but he was disorientated, and he attempted to get back on to his forklift, and then he lost consciousness again and this time he fell forward, striking his face on the ground.
"He was noticed by another worker, who raised the alarm."
In a reference to a leak of hydrogen sulphide at Tasman Tanning in 2012, Mr Stewart said businesses had to learn from their mistakes and ensure changes were effective.
"When a business is held to account for breaches of the law, ensuring the breaches aren't repeated is a cornerstone of good health and safety practice. Failing to do so is a breach of workers' rights to a safe workplace."
A chemical spill at the tannery in November 2012 saw 21 people affected by hydrogen sulphide gas, with the two worst-affected being flown to Wellington Hospital in a critical condition. In October 2013, the company admitted safety failures in the Whanganui court and was fined for the breaches.