Chart 1 The good days are getting worse and the bad days remain the same

Sources: Environment Canada, n.d. National Air Pollution Surveillance Program Data, based on hourly ground-level ozone concentration data, 1990 to 2005, (accessed April 30, 2008).
Environment Accounts and Statistics Division, 2007, 40-km population estimates, 1990 to 2005, based on Statistics Canada, Census of Population and Population Estimates Program, special tabulation.