FILE - In this Monday, Nov. 30, 2015 file photo, a woman wearing a mask to protect herself from pollutants walks out of an underpass tunnel in Beijing near a large video screen showing President Xi Jinping shaking hands with U.S. President Barack Obama at the climate talks in Paris, as the capital was shrouded in haze and monitoring sites throughout the city reporting extremely hazardous levels of pollutants. (AP Photo/Andy Wong)