Reporting from Washington - The Environmental Protection Agency proposed the nation's strictest-ever smog limits this morning, a move that could put large parts of the country in violation of federal air quality regulations. The EPA proposed allowing a ground-level ozone concentration of between 60 and 70 parts per billion, down from the 75-ppb standard adopted under President George W. Bush in 2008. That means cracking down even further on the emissions from power plants, factories, landfills and motor vehicles which bake in sunlight and form smog. Obama administration officials and environmental groups say the new standards align with the levels...