The federal Environmental Protection Agency is giving the public thirty more days to comment on a rule to regulate air pollution. Comments on the EPA’s proposed air toxics and mercury standards were initially due July 5, but now that’s been pushed back a month.In March, after a 20-year political and legal battle, the EPA proposed its first-ever national standards for regulating mercury and other air pollution from power plants. They say the rules will positively impact Americans’ health, but utility companies say they will drive up the cost of electricity.The EPA held public meetings on the proposed rule this spring in Chicago, Philadelphia and Atlanta. Here's how to submit a comment.