"Nitrous oxide (N20) emissions could almost double by 2050 if more aggressive action is not taken, undermining global efforts to curb climate change, the United Nations' Environment Programme (UNEP) said on Thursday."

"Winona will be the first U.S. city to monitor pollution from trucks hauling frac sand en route to fracking operations."

"MODESTO, Calif. – The students filing into Bret Harte Elementary School every morning barely notice the flags fluttering by the school's main entrance. There is the American flag, the California state flag and the color-coded asthma flag – green when the air is clear, red when it is a respiratory nightmare, as it so often is here."

"LOS ANGELES -- Wildfire smoke poses a growing health risk to millions of Americans, even for those who live hundreds of miles from the flames, a new report by an environmental group says."

"Dense, choking smog blanketed several northern cities yesterday, with visibility in some areas reduced to less than 10 metres. Drivers complained they were unable to see traffic lights."

"AUGUSTA — Delaware and New York are opposing Maine’s proposal to loosen its anti-smog regulations, claiming it violates federal law and undermines efforts to reduce ozone and other air pollution in eastern states."

"The air we breathe is laced with cancer-causing substances and is being officially classified as carcinogenic to humans, the World Health Organization's cancer agency said on Thursday."

"Exposure to even low levels of common air pollutants during pregnancy significantly increases the risk of babies being born small, according to one of the largest studies of its kind."

"BOSTON -- A Massachusetts power plant recently cited by federal regulators as one of the state's heaviest polluters is planning to shut down."

"TOPEKA, Kansas -- The Kansas Supreme Court Friday invalidated the 2010 air pollution permit granted to Sunflower Electric Power Corp. by the Kansas Department of Health and Environment."