Hazy days in China

A woman holds a child as travellers wait for the highway from Beijing to China's Hebei Province to reopen after in was closed due to low visibility, on a heavy polluted morning, August 3, 2015. REUTERS/Damir Sagolj

Travellers react as the highway from Beijing to China's Hebei Province is reopened, after in was closed due to low visibility on a heavy polluted morning, August 3, 2015. REUTERS/Damir Sagolj

An electronic screen is seen on a building amid heavy smog in Shenyang, Liaoning province, October 28, 2013. REUTERS/Stringer

A resident fishes on the bank of the Yangtze River near the Wuhan Yangtze River Bridge amid thick haze in Wuhan, Hubei province, June 15, 2012. REUTERS/Stringer

The China Central Television building is seen next to a construction site in heavy haze in Beijing's central business district, January 14, 2013.REUTERS/Jason Lee

A girl makes her way to her house which locates next to chimneys of coal-fired power plant in Shijiazhuang, Hebei province, January 28, 2015. REUTERS/Kim Kyung-Hoon

Tourists wearing masks visit Tiananmen Square in Beijing, March 9, 2013. REUTERS/Kim Kyung-Hoon

Reuters / Tuesday, May 15, 2012A view of downtown Shanghai on a hazy day, May 15, 2012. REUTERS/Carlos Barria

A staff member of the Beijing Municipal Environmental Protection Monitoring Center works at its monitoring room of the air quality forecast and warning center in Beijing, May 21, 2015. REUTERS/Kim Kyung-Hoon

A staff member of the Beijing Municipal Environmental Protection Monitoring Center works at its monitoring room of the air quality forecast and warning center in Beijing, May 21, 2015. REUTERS/Kim Kyung-Hoon

A group of expatriates walk along the Bund as they distribute face masks to pedestrians to raise awareness of air pollution in downtown Shanghai, January 24, 2013. REUTERS/Carlos Barria

statue of China's late Chairman Mao Zedong is seen in front of buildings during a hazy day in Shenyang, Liaoning province, May 7, 2013. REUTERS/Stringer

An elderly man exercises in the morning as he faces chimneys emitting smoke behind buildings across the Songhua river in Jilin, Jilin province, February 24, 2013. REUTERS/Stringer

A traffic policeman signals to drivers during a smoggy day in Harbin, Heilongjiang province, October 21, 2013. REUTERS/China Daily

The financial district of Pudong is seen on a hazy day in Shanghai, January 21, 2013. REUTERS/Aly Song

A woman walks along a street during a smoggy day in Changchun, Jilin province, October 22, 2013. REUTERS/China Daily

Woman wear face masks on the Bund in front of the Oriental Pearl TV Tower during a hazy day in downtown Shanghai, January 26, 2015. REUTERS/Aly Song

Shanghai's skyscrapers Shanghai World Financial Center (L), Shanghai Tower (R) and Jin Mao Tower (top) are seen at the financial district of Pudong during Earth Hour in Shanghai, March 29, 2014. REUTERS/Carlos Barria

A Chinese national flag flies in front of Beijing Telegraph Building on a hazy morning in central Beijing, February 28, 2013. REUTERS/Petar Kujundzic