EPA's advisory board recommended tightening regulations on pollution from diesel vehicles and power plants, but EPA decided against it

The stricter ozone standard spiked by White House might have had less than anticipated impact on business - and politics

New studies say standards for mercury, particulates could save thousands of lives

An international health body declared Tuesday that diesel engine exhaust is 'carcinogenic to humans.'

New report shows drought gripping US has expanded to cover widest area since drought of 1956