President Obama has overruled the EPA and directed EPA Administrator Lisa Jackson to withdraw a controversial proposed regulation tightening health-based standards for smog. Ozone is the main ingredient in smog.

The withdrawal of the proposed EPA rule comes three days after the White House identified seven such regulations that it said would cost private business at least $1 billion each. The proposed smog standard was estimated to cost anywhere between $19 billion and $90 billion, depending on its strictness.

House Republicans had pledged to try to block four environmental regulations, including the one on some pollution standards, when they return after Labor Day. Perhaps more than some of the other regulations under attack, the ground-level ozone standard is most closely associated with public health — something the president said he wouldn't compromise in his regulatory review.

In his statement, the president said that withdrawing the regulation did not reflect a weakening of his commitment to protecting public health and the environment. "I will continue to stand with the hardworking men and women at the EPA as they strive every day to hold polluters accountable and protect our families from harmful pollution," he said.

The decision mirrors one made by Obama's predecessor, President George W. Bush. EPA scientists had recommended a stricter standard to better protect public health. Bush personally intervened after hearing complaints from electric utilities and other affected industries. His EPA set a standard of 75 parts per billion, stricter than one adopted in 1997, but not as strong as federal scientists said was needed to protect public health.

The EPA under President Obama proposed in Jan. 2010 a range for the concentration of ground-level ozone allowed in the air — from 60 parts per billion to 70 parts per billion.