The U.S. may breathe a little easier. Obama plans to announce new EPA rules slashing ground-level ozone, aka smog, from 75 parts per billion to 65-70 range. Some industry leaders say the new regulations will be so costly they could potentially harm the economy. The announcement comes a day after the Supreme Court agreed to hear arguments against other EPA rules requiring power plants to scale back air pollutants. The court ruling, and the new guidelines, won’t come until next year.