A looming Obama administration rule aimed at updating the federal ozone standard could be the single most expensive federal regulation in U.S. history, according to a new study commissioned by the National Association of Manufacturers (NAM). The proposal, expected to be unveiled by year’s end, could lead to millions of lost jobs, $2.2 trillion in compliance costs and a $3.4 trillion blow to gross domestic product between 2017 and 2040, according to the 142-page study. The analysis does not take potential public health benefits into account. NAM President Jay Timmons contends the regulation would saddle manufacturers with a new regulatory...