Metro Vancouver is changing the way it charges fees to companies that produce industrial emissions.

In a policy shift that takes effect immediately, the costs companies pay will be based on the type of emissions they discharge, not simply on the amount of the discharge.

Under the old system, "two facilities could be paying very similar fees and distributing vastly different amounts of material and vastly different harmfulness," Raymond Robb, a regulation and enforcement manager with Metro Vancouver, told CBC News.

But under the new rules, the more harmful the emissions, the higher the price per tonne of contaminant, said Port Moody Mayor Joe Trasolini, chair of the environment and energy committee of Metro Vancouver.

The new system "imposes higher fees for more dangerous contaminants that are emitted," Trasolini said. "For example, if you're emitting dust, that's one thing. But if you're emitting more dangerous contaminants, then the fee changes."

Trasolini said that while the intent of the new regulations is to improve air quality, he couldn't guarantee that would be the result.

However, he added, they will at least "safeguard the quality of air we have."

Greenhouses and farms in the Lower Mainland will be exempt from the new emission policy, at least until Metro Vancouver staff can prepare a report for the board on the types of pollutants they expel.