A Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' 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 than 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)

Cadets from the National Cadet Corps (NCC) celebrate after being awarded the first position in the best marching trophy competition during the Republic Day celebrations in the northern Indian city of Chandigarh January 26, 2015. (Photo by Ajay Verma/Reuters)

An Indian woman wrapped in a shawl travels with others on a bullock cart on a cold day at Jhansi district, in Bundelkhand, India, Monday, December 29, 2014. Most parts of north India Monday continued to shiver under biting cold with the mercury dipping several notches. (Photo by Rajesh Kumar Singh/AP Photo)

Meerkats are weighed and measured during the ZSL London Zoo 's annual weigh-in on August 22, 2012 in London, England. The height and mass of every animal in the zoo, of which there are over 16,000, needs to be recorded. The measurements are collated in the Zoological Information Management System, from which zoologists can use the data to compare information on thousands of endangered species. (Photo by Oli Scarff)

Chinese artist Kong Ning walks in her costume made of hundreds of orange plastic blowing horns during her art performance raising awareness of the hazardous smog in front of the Drum tower in a historical part of Beijing on a very polluted day December 7, 2015. Kong, whose works include themes related to China's air pollution problem, named her new performance “The Orange Horns Bride Marries the Blue Sky” and presented it dressed in orange, the colour of the second highest pollution alert level issued again in Beijing as hazardous smog blankets the capital. (Photo by Damir Sagolj/Reuters)

A police poses on the durians during festival durian on the giant mount of durian at northern slopes of Mount Arjuna in East Java. Each year, nine villages in Wonosalam district hold a festival to give thanks for an abundance of this stinky, spiky fruit, which they pile in a 10-meter-high pyramid and distribute among the hungry masses. (Photo by Sigit Pamungkas/JG Photo)

A stray puppy walks along abandoned train tracks near the Chernobyl nuclear power plant on August 19, 2017 near Chornobyl, Ukraine. An estimated 900 stray dogs live in the exclusion zone, many of them likely the descendants of dogs left behind following the mass evacuation of residents in the aftermath of the 1986 nuclear disaster at Chernobyl. (Photo by Sean Gallup/Getty Images)

A shrine maiden walks in the snow at the Tsurugaoka Hachimangu Shrine in Kamakura, near Tokyo, Thursday, November 24, 2016. Tokyo residents have woken up to the first November snowfall in more than 50 years. An unusually cold air mass brought wet snow to Japan's capital on Thursday. Above-freezing temperatures kept the snow from sticking, but forecasters said there could be an accumulation of up to 2 centimeters (1 inch). The last time it snowed in central Tokyo in November was in 1962. (Photo by Shizuo Kambayashi/AP Photo)