WASHINGTON (Reuters) - The Obama administration on Thursday will issue new limits on ground-level ozone, the main component of smog, as officials try to promote human health without unduly burdening industry with costly regulations, sources familiar with the plan said.
Advocates expect the Environmental Protection Agency (EPA) to set the new national ozone standard at a level between 65 and 70 parts per billion (ppb), tightening the current level of 75 ppb set under former President George W. Bush in 2008.
Officials are likely to publicly announce the ozone threshold and explain their thinking by mid-afternoon, two sources briefed on the plans said.
As they deliberated the new plan's impact, officials had to contemplate billion-dollar costs to industry as well as the effect on thousands of peoples' health.
A 65 ppb cap would cost industry about $11 billion more to implement than a 70 ppb limit but prevent three times as many childhood asthma attacks, according to EPA estimates.
The 65 ppb threshold would prevent 960,000 childhood asthma attacks compared to 320,000 incidents at the 70 ppb level, the EPA predicts, while industry would face costs of $3.9 billion if the pollution limit were at the high end.
Under the proposal, U.S. states would likely have several years to work with power plants, factories and refineries to limit pollutants like nitrogen oxide and volatile organic compounds - the components of health-damaging smog.
The final rule comes after months of intense lobbying from industry groups, who warned that a stringent ozone rule would harm the economy even more than a sweeping plan to limit carbon emissions from power plants. The power plant rule is at the center of President Barack Obama's climate change strategy.
(Reporting By Valerie Volcovici, Timothy Gardner and Patrick Rucker; Editing by Christian Plumb)