A woman wearing a scarf to cover her face looks on as she waits for a passenger bus on a smoggy morning in New Delhi, India, November 8, 2017. The Great Smog of Delhi is an ongoing severe air-pollution event in New Delhi and adjoining areas in the National Capital Territory of India, in November 2017. Air pollution at this time peaked on both PM 2.5 and PM 10 levels. It has been reported as one of the worst levels of air quality in Delhi since 1999. (Photo by Saumya Khandelwal/Reuters)

Aerial view of pond cypress at Qinglongwan Forest Park near Ningguo, China on November 26, 2017. (Photo by Imaginechina/Rex Features/Shutterstock)

A Kashmiri Muslim woman balances on a water pipe before collecting water at Dasilpora village on March 22, 2018. World Water Day is held annually on 22 March as a means of focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources. (Photo by Tauseef Mustafa/AFP Photo)

Thousands of heavy-duty trucks loaded with coal are lined up for up to 130 kilometres from the Mongolia-China border on a sole road in the Gobi desert, Mongolia, October 29, 2017. The journey can take more than a week. (Photo by Bazarsukh Rentsendorj/Reuters)

A worker spreads paddy crop for drying in a rice mill complex on the outskirts of Ahmedabad February 3, 2011. (Photo by Amit Dave/Reuters)

A boy looks for scrap metal using an improvised magnetic tool near a construction site in New Delhi, India, March 21, 2016. (Photo by Cathal McNaughton/Reuters)

A woman cries after her husband was shot dead by unidentified gunmen riding motorcycles in Manila, Philippines late October 10, 2016. According to police reports, around 2,300 people have been killed in Philippine President Rodrigo Duterte's war against illegal drugs. The figure was revised by the police from an original tally of around 3,600 deaths. (Photo by Damir Sagolj/Reuters)

A Filipino transgender woman holds a huge red ribbon symbolizing fight against the HIV virus as she poses before photographers, during a World Aids Day celebration in Manila, Philippines, December 1, 2015. (Photo by Erik De Castro/Reuters)