A company's bid to release a highly toxic gas into Tauranga's atmosphere has been quashed after environmental regulators found that its use has already reached "worrying" levels.
The Environment Court blocked an application by Envirofume Ltd to fumigate logs for export using methyl bromide at the Port of Tauranga.
Envirofume wanted to pump the gas into logs while they lay under tarpaulins, a method that lets some escape into the atmosphere and waft into surrounding areas. The company altered its application to allow gas to escape at a one to 14 ratio with air using a fan system, but the court still said no.
Use of the gas at Port Nelson was suspected to have caused the deaths of up to six people who contracted motor neurone disease between 2002 and 2005, although medical reports reached conflicting conclusions.
In its decision, the court rejected Envirofume's application but noted that another company, Genera, continued to use methyl bromide at the port. Genera can release the gas so long as it does not exceed set limits at the port's boundary.
The court said measurements had found "worrying" quantities of the gas at the port's boundary of more than 10 times a limit set by the US Centre for Disease Control.
The court described the health effects of methyl bromide as "chilling" and said it had "no confidence" that its current use at the port was meeting standards set by New Zealand's Environmental Protection Authority.
Safer gases including phosphine are being used to fumigate logs in some New Zealand ports, but countries including India and China insist that imported logs be treated with methyl bromide.
A field worker for motor neurone disease charity MND, Graham Jones, said the disease was usually fatal within three to five years of being diagnosed as muscles wasted away and respiratory failure set in.
Mr Jones knew of 22 cases in Tauranga currently, but none associated with the port.
The Green Party praised the decision but called on authorities to investigate the continuing use of the gas.
The Greens' pesticide and biosecurity spokesman, Steffan Browning, said residents near the ports of Tauranga, Napier and Whangarei were still being exposed to the gas because it was not being fully contained, or "recaptured", during use.
"We shouldn't be exposing people to this stuff," Mr Browning said.
"It's colourless and odourless, and people don't even know if they've inhaled it until well down the track."
Envirofume directors could not be contacted. Genera did not respond in time for this story.
● Is colourless, odourless and non-flammable
● Is ozone-depleting
● Has been used as a pesticide
● Has been phased out of use in many countries
● Is restricted under the Montreal Protocol