Satellite data from NASA shows the concentration of the carbon monoxide drifting eastward from California.
From pasteurized milk to saving bees from extinction, the remedy is often worse than the ailment.
Obama used the Clean Air Act's provisions to allow the EPA to create the Clean Power Plan.
Experts couldn't measure just how bad the air pollution was because the sandstorm caused traditional measuring instruments to break.
Paris joins Athens, Madrid and Mexico City in banning diesel by 2025.