The McNeil government has granted permission to the Lafarge Canada Inc. cement plant in Brookfield, N.S., to burn tires as fuel for 12 months.

Nova Scotia Environment Minister Margaret Miller said Wednesday the decision by her department was based on "science and evidence."

"We know this isn't the very first time that tires have ever been used for fuel for a low carbon source of fuel," she told reporters on her way into Province House.

The industrial approval document, released by the Department of Environment, says LaFarge will need to monitor air quality and ensure there is no groundwater contamination. The company is expected to shoulder the costs of those measures.

During the year-long trial Lafarge will be limited to burning tires to a maximum of 15 per cent of its daily fuel needs or a 20 tonne per day limit.

Dalhousie University researchers will monitor the company's use of tires as a replacement fuel to coal. Last year the company's environmental director, Robert Cummings, predicted the change could "achieve a 30 per cent reduction in carbon emissions for every tonne of coal" replaced.

But on Wednesday NDP environment critic Lenore Zann called the province's decision to issue the approval "absolutely ludicrous."

"I just think it's ridiculous that we're trying to mess with people's lives," she told reporters. "We're doing an experiment about burning tires in 2018."

Mark Butler, policy director at the Ecology Action Centre, also criticized the move and the environment minister's claim it is a greener way to go.

"You have to look at the overall emissions for the province not just the emissions from that particular plant, and if you do that you see that it doesn't do much, if anything, to reduce our overall greenhouse gas emissions," he said.

Nova Scotians who replace their tires pay a $4-a-tire recycling fee that is supposed to go towards programs designed to reuse or recycle them. Lafarge will be getting a portion of that fee to dispose of the tires it will burn, but Premier Stephen McNeil rejected the notion the money is a subsidy.

"I don't see it as a subsidy," he said. " We see this as reducing our environmental footprint from burning coal.

"It's recycling in a different way."

Although a government news release said 10-year industrial approvals were the norm, Lafarge spokesperson Karine Cousineau dismissed the suggestion the company had asked for anything more than what it received.

The one-year term was "consistent with what we applied for," she said in an email.

"We are pleased to have reached a new milestone in our national program to replace fossil fuels with lower carbon fuels," she wrote.

The decision in July 2017 to issue an environmental assessment approval for the project, an initial step in the approval process, drew criticism from environmentalists and nearby residents, from Nova Scotia's only tire recycler at the time, Halifax C&D Recycling Ltd., and from the NDP.

New Democrat Leader Gary Burrill called it "dense, dumb and stupid."