It wasn’t always easy, deadlines were missed, and not everybody agreed with how it was done, but over the past 10 years, the Canadian province of Ontario has shown that it’s possible to wean a large economy off coal. In 2003, the province had 7.5 gigawatts of coal capacity, burning 18.6 million metric tons of the black stuff annually. This year, the last big coal-fired units are scheduled for closure (just since 2010 about 3 gigawatts of coal has been shut down), and after that two smaller coal-powered units which generate a combined 300MW of power should close next year.
Apart from lower greenhouse gas emissions, this has had a positive impact on air quality:
According to the Ministry of the Environment, from 2000 to 2010, air quality improved province-wide in Ontario, and the phasing out of coal plants was a key reason. Ontario also implemented programs to reduce emissions from smelting plants and reduce particulates and toxic air contaminants from the transport sector. Overall, mean particulate concentrations in the province’s air fell from 8.1 micrograms per cubic meter in 2003 to 4.8 micrograms per cubic meter in 2010, a 40 percent decline. (source)