I just read an opinion piece about this recently:

EPA jumps the gun with job-killing rules
Agency’s new blow to air-quality standard comes two years early
washingtontimes.com

Twice this year, President Obama asked federal agencies to review regulations to ensure that they are not interfering with efforts to rebuild the U.S. economy. In January, he signed an executive order directing agencies to use the “least burdensome tools” that take “into account benefits and cost” and “[promote] economic growth … and job creation.”

Either the Environmental Protection Agency didn’t get the memo or it was lost under the growing stack of regulations the agency is advancing at record speed.

Last week, the EPA said it would soon release updated ozone regulations that are going to kill jobs and impose substantial costs on the U.S. economy - at least $90 billion, by its own estimates, and $1 trillion annually between 2020 and 2030 according to industry estimates.

The important part:

n 1997, the Clinton administration set an eight-hour ozone standard of 84 parts per billion. By 2004, there were still 474 counties that had not achieved that goal. Today, just 242 counties aren’t meeting the standard. In 2008, the Bush administration set an even stricter standard that lowered the ozone level to 75 parts per billion. Small businesses are still in the process of implementing technologies to comply with that ruling. Yet the EPA now wants to ratchet down emissions to between 60 and 70 parts per billion.

At those points, the number of nonattainment counties - places with ozone levels that exceed the “‘acceptable” amount - would increase from 242 to between 515 and 650, depending on where the new bar is set.