BEIJING, CHINA - DECEMBER 09:  Women wear masks to protect against pollution as they visit Tiananmen Square during smog in Tiananmen Square on December 9, 2015 in Beijing, China. The Beijing government issued a 'red alert' Sunday for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower then last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change.  (Photo by Kevin Frayer/Getty Images)