Ontario submitted a friend of the court brief to the U.S. Court of Appeals for the District of Columbia Circuit May 1, contending that areas of the province near the U.S. border cannot meet their ozone air quality standard because of power plant pollution that crosses into Canada. The province is supporting U.S. states and advocacy groups that are challenging the 2008 national ambient air quality standard for ozone of 0.075 ppm as not protective enough. The province is closing all of its coal-fired power plants by 2014, but will still not meet its 0.065 ppm standard because of U.S. pollution.