The U.S. Environmental Protection Agency has proposed the strictest health standards to date for smog in the United States.
The proposed range of 60-70 parts per billion during an eight-hour period is what scientists recommended during the former Bush administration. However, after industries protested, then-President George W. Bush intervened to set the standard above what was advised.
The new, lower smog standard will undergo 60 days of public comment before it becomes official.
The EPA says the estimated costs of meeting the new standard range from $19- 90 billion. However, the agency says the savings from improved health should also number in the billions of dollars.
The agency says smog, also known as ground-level ozone, is linked to serious health problems like asthma and can increase the risk of premature death in people with heart or lung disease.
Advocates say the stricter smog standard is expected to reduce emergency room visits and missed days of work and school.
Smog forms when emissions from industrial facilities, power plants, landfills and motor vehicles react in the sun.
Some information for this report was provided by AP.