In an ongoing effort to burnish its environmental reputation, the federal government has released a report Friday showing that emissions of a number of harmful pollutants fell in 2011 compared to 2010.

Emissions of the heavy metals mercury, lead and cadmium were down 23 per cent, 21 per cent and 50 per cent respectively from the year before, according to the latest air pollutant emission summaries and trends data published by Environment Canada.

The reductions were because of a reduction in activity in the smelting and upstream oil and gas industries.

Data published Friday by Environment Canada shows that emissions of several pollutants, including key ingregients in smog, fell in 2011 compared to 2010. (Adrian Wyld/Canadian Press)

Emissions of sulphur oxides, one of the components of smog, were down seven per cent, mainly because of reductions in emissions from metal smelters and fossil-fueled electiricity generation, but also due to an overall reduction in the industrial sector.

Another contributor to smog, nitrogen oxides, was also down six per cent because of fewer emissions from mobile sources and less electricity power generation from fossil fuels such as coal.

Green Party leader Elizabeth May, in a written statement on Friday, said this report doesn't give Conservatives bragging rights over environmental policies.

“This report has nothing to do with the crisis of climate change and in no way vindicates the Conservatives and their anti-environment policies of the past six years."

The Green Party leader pointed to last week's report by Environment Commissioner Scott Vaughan. May said the watchdog noted "the National Pollutant Release Inventory actually exempts releases from oil and gas exploration and development."

"The report also contains no emission information regarding hundreds of thousands of hydraulic fracturing – or fracking – projects across the country," said May.

The emissions report comes during a week in which the U.S. president has been placing a new emphasis on combating climate change.

Obama puts focus climate change battle

Barack Obama is vowing to deal with the issue, if Congress does not come up with its own market-based solution. That could mean a carbon tax, or a cap-and-trade system, that would force companies to buy and sell credits for cutting greenhouse gas emissions.

Canada has said it is opposed to both of those ideas. Yet at the same time, it has promised to implement whatever climate change efforts the U.S. imposes, because of the ties between the two markets.

Federal Natural Resources Minister Joe Oliver wouldn't comment on the U.S. plans, saying it was all speculation for now.

But he said Ottawa will have regulations soon that will cover the oil and gas sector, including the oilsands. Oliver said the regulations are not being drafted to appease the U.S.

"And that will send a signal not only to the Americans but to the world that we're very serious about this issue," Oliver said.

But the NDP's environment critic, Megan Leslie, said that's not going to be enough when the U.S. moves to put a price on carbon.

"When this does happen, I think they are going to have egg on their faces and it's going to be a huge scramble to recover," Leslie told CBC Thursday.

Environment Canada's website says the emission summaries and trends data are based on information reported by industry to the National Pollutant Release Inventory under the Canadian Environmental Protection Act, as well as emission estimates for other sources such as motor vehicles, agricultural activities and forest fires.