Birds fly next to electricity pylons on a smoggy afternoon in the old quarters of Delhi, India, October 30, 2019. REUTERS/Adnan Abidi

Birds fly next to electricity pylons on a smoggy afternoon in the old quarters of Delhi, India, October 30, 2019. REUTERS/Adnan Abidi TPX IMAGES OF THE DAY

A man carrying a basket walks along the paddy fields early in the morning in Bhaktapur, Nepal, October 27, 2019. REUTERS/Monika Deupala

Olive trees stand in a grove in Porcuna, southern Spain October 15, 2019. Picture taken October 15, 2019. REUTERS/Marcelo del Pozo

A view of Beppu from the Beppu Bay Service Area, Japan, October 14, 2019. REUTERS/Peter Cziborra

Fog rises over a village in the mountainous district of Haraz, around 90 kilometers southwest of Sanaa, Yemen October 2, 2019. Picture taken October 2, 2019. REUTERS/Khaled Abdullah

A village is shrouded by fog in the mountainous district of Haraz, around 90 kilometers southwest of Sanaa, Yemen October 2, 2019. Picture taken October 2, 2019. REUTERS/Khaled Abdullah

Fog rises above a village in the mountainous district of Haraz, around 90 kilometers southwest of Sanaa, Yemen October 2, 2019. Picture taken October 2, 2019. REUTERS/Khaled Abdullah

A general view of the urban landscape of Tel Aviv as most Israeli Jews refrain from driving during the 25-hour period of Yom Kippur, Israel October 9, 2019. REUTERS/Ammar Awad

A morning fog is seen in the Siberian city of Omsk, Russia October 8, 2019. Picture taken October 8, 2019. REUTERS/Alexey Malgavko TPX IMAGES OF THE DAY

People are seen through a window as waves hit the coast of Sao Mateus, as Hurricane Lorenzo hits the Azores islands, in Azores, Portugal October 2, 2019. REUTERS/Rafael Marchante TPX IMAGES OF THE DAY

People are seen ahead of Pope Francis' arrival for a prayer vigil with youth at the Soamandrakizay Mess site in Antananarivo, Madagascar, September 7, 2019. REUTERS/Yara Nardi

Men walk along a street on a foggy morning in the old quarters of Delhi, India, December 31, 2018. REUTERS/Anushree Fadnavis TPX IMAGES OF THE DAY

A man paddles a handmade boat across the Yamuna river on a foggy winter morning in New Delhi, India December 27, 2018. REUTERS/Adnan Abidi TPX IMAGES OF THE DAY

Windows take on different shapes as they reflect upon the water along a wharf in Portland, Maine, U.S., December 24, 2018. REUTERS/Kevin Lamarque TPX IMAGES OF THE DAY

Thousands of starlings fly in a 'murmuration' as they return to roost at dusk near Ely in Cambridgeshire, Britain December 24, 2018. REUTERS/Hannah McKay TPX IMAGES OF THE DAY

A man feeds seagulls as he stands on the banks of Yamuna river on a foggy winter morning in New Delhi, India, December 24, 2018. REUTERS/Adnan Abidi TPX IMAGES OF THE DAY

The sunset is seen during a poor air quality day in Bangkok, Thailand, December 21, 2018. REUTERS/Jorge Silva TPX IMAGES OF THE DAY

A man walks through a vegetable field on a foggy winter morning in New Delhi, India, December 18, 2018. REUTERS/Anushree Fadnavis TPX IMAGES OF THE DAY

A man walks through a vegetable field on a foggy winter morning in New Delhi, India, December 18, 2018. REUTERS/Anushree Fadnavis

People walk on a pedestrian bridge as heavy smog blankets China's capital after the city issued its first air pollution alert for the winter season, in Beijing, China November 26, 2018. REUTERS/Jason Lee TPX IMAGES OF THE DAY

People walk on a pedestrian bridge as heavy smog blankets China's capital after the city issued its first air pollution alert for the winter season, in Beijing, China November 26, 2018. REUTERS/Jason Lee

Protesters wearing yellow vests, a symbol of a French drivers' protest against higher fuel prices, are seen during riots on the Champs-Elysees in Paris, France, November 24, 2018. REUTERS/Gonzalo Fuentes

Clouds can be seen above a dust storm as it descends upon the city of Sydney in Australia, November 22, 2018. Picture taken through the window. REUTERS/David Gray

Snow covered trees are seen on a foggy day in the Buda hills in Budapest, Hungary, November 19, 2018. REUTERS/Bernadett Szabo

People walk on a foggy day in the Buda hills in Budapest, Hungary, November 19, 2018. REUTERS/Bernadett Szabo

Snow covered trees are seen on a foggy day in the Buda hills in Budapest, Hungary, November 19, 2018. REUTERS/Bernadett Szabo

Snow covered trees are seen on a foggy day in the Buda hills in Budapest, Hungary, November 19, 2018. REUTERS/Bernadett Szabo

Snow covered trees are seen on a foggy day in the Buda hills in Budapest, Hungary, November 19, 2018. REUTERS/Bernadett Szabo

Heavy fog covers the city of Minsk, Belarus November 9, 2018. REUTERS/Vasily Fedosenko TPX IMAGES OF THE DAY

Heavy fog covers the city of Minsk, Belarus November 9, 2018. REUTERS/Vasily Fedosenko

Heavy fog covers the city of Minsk, Belarus November 9, 2018. REUTERS/Vasily Fedosenko

Heavy fog covers the city of Minsk, Belarus November 9, 2018. REUTERS/Vasily Fedosenko

Heavy fog covers the city of Minsk, Belarus November 9, 2018. REUTERS/Vasily Fedosenko

Sunlight reflects from windows of an apartment building on a foggy autumn day in Kiev, Ukraine November 8, 2018. REUTERS/Valentyn Ogirenko TPX IMAGES OF THE DAY

Sunlight reflects from windows of an apartment building on a foggy autumn day in Kiev, Ukraine November 8, 2018. REUTERS/Valentyn Ogirenko TPX IMAGES OF THE DAY

Sunlight reflects from windows of an apartment building on a foggy autumn day in Kiev, Ukraine November 8, 2018. REUTERS/Valentyn Ogirenko TPX IMAGES OF THE DAY

A bird flies in a front of an orthodox church on a foggy autumn day in Kiev, Ukraine November 8, 2018. REUTERS/Valentyn Ogirenko

Sunlight reflects from windows of an apartment building on a foggy autumn day in Kiev, Ukraine November 8, 2018. REUTERS/Valentyn Ogirenko

A man with his face covered walks in front of the India Gate amidst smog in the early morning in New Delhi, India, November 8, 2018. REUTERS/Anushree Fadnavis TPX IMAGES OF THE DAY

A man wearing a protective mask walks amidst smog in the early morning in New Delhi, India, November 8, 2018. REUTERS/Anushree Fadnavis

Buildings are seen shrouded in smog in New Delhi, India, November 8, 2018. REUTERS/Anushree Fadnavis

A man crosses a road on a smoggy morning in New Delhi, India, November 8, 2018. REUTERS/Anushree Fadnavis

A Georgia State Patrol Officer guards the ballroom at Republican gubernatorial candidate Brian Kemp's election night party in Athens, Georgia, U.S. November 6, 2018. REUTERS/Chris Aluka Berry TPX IMAGES OF THE DAY

Residential buildings are seen shrouded in smog in Noida on the outskirts of New Delhi, India, November 5, 2018. REUTERS/Malini Menon

A cooling tower and chimneys are seen at a thermal power plant on a polluted day in Beijing, China, November 3, 2018. REUTERS/Jason Lee

Apartment blocks are seen on the outskirts of Langfang, Hebei province, China, November 3, 2018. REUTERS/Jason Lee

A man walks in front of the India Gate shrouded in smog in New Delhi, India, October 29, 2018. REUTERS/Anushree Fadnavis TPX IMAGES OF THE DAY

A spider crawls through its net facing the skyline with its financial distric on early evening in Frankfurt, Germany, October 5, 2018. REUTERS/Kai Pfaffenbach

Catalan separatist protesters clash with Mossos d'Esquadra police officers as they protest against a demonstration in support of the Spanish police units who took part in the operation to prevent the independence referendum in Catalonia on October 1, 2017, in Barcelona, Spain, September 29, 2018. REUTERS/Albert Gea

Catalan separatist protesters clash with Mossos d'Esquadra police officers as they protest against a demonstration in support to the Spanish police units who took part in the operation to prevent the independence referendum in Catalonia on October 1 2017, in Barcelona, Spain, September 29, 2018. REUTERS/Albert Gea

A Beluga whale swims in the River Thames near Gravesend, east of London, Britain, September 26, 2018. REUTERS/Peter Nicholls

A Beluga whale swims in the River Thames near Gravesend, east of London, Britain, September 26, 2018. REUTERS/Peter Nicholls

A Beluga whale swims in the River Thames near Gravesend, east of London, Britain, September 26, 2018. REUTERS/Peter Nicholls

A Beluga whale swims in the River Thames near Gravesend, east of London, Britain, September 26, 2018. REUTERS/Peter Nicholls

A Beluga whale swims in the River Thames near Gravesend, east of London, Britain, September 26, 2018. REUTERS/Peter Nicholls

A Beluga whale swims in the River Thames near Gravesend, east of London, Britain, September 26, 2018. REUTERS/Peter Nicholls

A Beluga whale swims in the Thames near Gravesend, east of London, Britain, September 26, 2018. REUTERS/Peter Nicholls

A Beluga whale swims in the River Thames near Gravesend, east of London, Britain, September 26, 2018. REUTERS/Peter Nicholls

A view from Chorrillos district shows buildings in Lima, Peru September 25, 2018. REUTERS/Mariana Bazo