The federal government's proposal to reduce smog will harm Pennsylvania manufacturers and the state's broader economy, pro-business groups are warning in a new public-relations offensive against the upcoming regulations.

At least 33 of Pennsylvania's 67 counties would be in violation of stricter emissions limits on smog-forming ozone, triggering mandatory curbs that could discourage factories from opening or expanding, stifle the natural gas industry, force delays in highway and bridge construction, and lead to expanded emissions testing for cars and trucks, according to a report by the Center for Regulatory Solutions.The rule "could stall Pennsylvania's recovery from the Great Recession and deny the commonwealth a long-awaited comeback in manufacturing jobs," said the report, obtained by The Associated Press ahead of its release today.The Obama administration plans to finalize its ozone regulation by Oct. 1. The Environmental Protection Agency is proposing an emission limit of 65 to 70 parts per billion, saying a reduction in the existing standard of 75 parts per billion that's been in place since 2008 will save lives and cut emergency-room visits. The administration of Democratic Gov. Tom Wolf supports the stricter standard.Health and environmental groups want the EPA to reduce emissions even more, to 60 parts per billion, arguing the range proposed by the EPA does not do enough to protect children, the elderly and other vulnerable populations."Every time the EPA has updated the limits on dangerous air pollutants, polluters and their allies deny the health benefits and claim the costs will be sky-high. We've heard these same arguments from industry groups, and they've been proven wrong time and time again," Deborah Brown, head of the American Lung Association in Pennsylvania, said.Ozone, the main ingredient in smog, has been linked to a range of health problems, including asthma and bronchitis. Culprits include vehicle exhaust, power plants, refineries and other factories.Pennsylvania has already seen significant improvements in air quality. The state reported more than seven times as many dangerous ozone days in 1999 than in 2014, a reflection of more stringent vehicle emissions regulations and a transition to cleaner-burning fuels.Business groups say the latest ozone rule would kill jobs while providing little additional benefit to public health. The report contends the stricter smog standard would handcuff growth in counties that, together, represent 85 percent of Pennsylvania's economy, including the cities of Philadelphia, Pittsburgh, Allentown, Erie, Harrisburg, Williamsport, Johnstown, Bethlehem, Easton and Scranton."We've had one of the worst recoveries on record and we don't need these added costs to further slow things down," said Ray Keating, chief economist with the Small Business and Entrepreneurship Council, a Washington-based lobbying group that funded the report.The group issued similar warnings for Ohio and Colorado last month.The EPA has estimated that cutting ozone emissions to 70 parts per billion would cost U.S. industry about $3.9 billion in 2025, while a stricter limit of 65 would cost up to $15 billion. That would make it the most expensive environmental regulation in U.S. history.