he observes,pointing to the very substantial cuts in air pollution emissions during the 2008 summer Olympics in the Beijing metropolitan area.

VOA: standard.2010.04.07

Every summer an extra area of ice six times the size of California has been disappearing.

ECONOMIST: An imminent answer to an Arctic riddle

For the past three years, the vast cap of shining-white ice covering the Arctic has melted away in summer to an area that would have been unbelievable just a decade ago.

ECONOMIST: An imminent answer to an Arctic riddle

And arid conditions, especially during the summer, leave the area without much rainfall to rinse the muck out of the air.

FORBES: The Worst Cities In America For Your Lungs