TORONTO - Ontario must stop exporting power from its coal-fired plants because the cash it generates isn't worth the toll that dirty air is taking on people's health, a group of doctors and environmentalists said Monday.

Jack Gibbons, chair of the Ontario Clean Air Coalition, said the province exported 20 per cent of its power last year, making a profit of $100 million. While that might have shaved 77 cents off the monthly bill of the average energy user, he said polluting Ontario's air wasn't worth it.

"Saving lives and preventing up to 65,000 asthma attacks is more important than a 77-cent reduction in our monthly electricity bills,'' Gibbons said, adding the Liberals promised to ban the export of non-emergency coal-fired electricity in the last election.

"It is time for Premier McGuinty to keep his promise.''

The Liberals, who initially promised to shutter Ontario's coal-fired plants by the end of their first mandate, have drafted a regulation that would see the remaining four plants close by 2014. They have also said some could close earlier.

Franz Hartmann, executive director of the Toronto Environmental Alliance, said the government argues the coal plants must stay open in the meantime because they are vital to keeping the province's lights on.

But Hartmann said Ontario could end its coal exports immediately without affecting the power supply, since the province's domestic needs are met primarily through other power sources like hydro and nuclear power.

"This coal-fired electricity wasn't made to keep the lights on or the air conditioners running in Ontario,'' he said of the province's exported power. "It was made to be sent south of the border to make money for Ontario Power Generation.''

Steve Erwin, spokesman for Energy Minister Dwight Duncan, said a mix of Ontario's power is exported but neither he nor OPG could say how much of that comes from coal.

Cutting off Ontario's exports to Canada's southern neighbours wouldn't necessarily make the province's air any cleaner, Erwin added. Without power from Ontario, the U.S. would likely step up production at its own coal plants, he said.

Instead, Erwin said the Liberals are putting the closure of coal plants into law and are starting to reduce the province's reliance on that kind of power.

"Coal power use overall is down by one-third,'' he said. "We're just continuing with that trend.''

But phasing out coal-fired power can't happen fast enough for Hilary de Veber, a Toronto pediatrician who regularly sees children with breathing difficulties and most recently treated a two-year-old boy she felt was close to death.

Children are particularly vulnerable to smog because they breathe in more air per kilogram than adults, she said.

"Smog kills,'' said de Veber, who is also with the Canadian Association of Physicians for the Environment. "When it is not killing people, it is reducing the health of all Ontarians through its many adverse health effects.''

Conservative Laurie Scott said the province should focus on cleaning up emissions coming from coal-fired plants rather than banning certain power exports. The Liberals could have put scrubbers on the plants several years ago which would have helped clean up the air, she said.

"The U.S. sends us energy when we need it,'' she said. "If there is a time when we have a supply of energy and they need it, that is something we would do as a neighbourly gesture -- they help us, we help them.

"we all need to work together to replace coal-fired energy.''

New Democrat Peter Tabuns said there is no good reason why the Liberals shouldn't ban the export of non-emergency coal-fired power.

"If you were committed to dealing with climate change and you knew you were increasing greenhouse gas emissions through these exports that didn't affect power supply in Ontario, you'd stop exporting that power,'' he said.