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)

A model wears a floral head dress as she promotes a chain of garden centres at the Royal Horticultural Soceity's Chelsea Flower Show in London, Britain, May 18, 2015. (Photo by Toby Melville/Reuters)

Vehicle lights illuminate a street after a massive blackout, in San Juan, Puerto Rico, Thursday, September 22, 2016. Puerto Ricans faced another night of darkness Thursday as crews slowly restored electricity a day after a fire at a power plant caused the aging utility grid to fail and blacked out the entire island. (Photo by Carlos Giusti/AP Photo)

A woman eats and struggles with her umbrella against powerful gusts of wind generated by typhoon Megi across the the island in Taipei, Taiwan, Tuesday, September 27, 2016. Schools and offices have been closed on Taiwan and people in dangerous areas have been evacuated as a large typhoon with 162 kilometers (100 miles) per-hour winds approaches the island. (Photo by Chiang Ying-ying/AP Photo)

Rusting old petrol pumps outside a long-closed rural village petrol station are seen on a minor road near Trowbridge, Britain, October 21, 2016. From art deco apartments in Sussex to a trendy burger bar in London, some of England's former petrol stations are enjoying a new lease of life following creative makeovers. The overhaul opportunities have been created as more than 20,000 stations closed in the United Kingdom over the past 40 years, according to the U.K.'s Petroleum Industry Association (PIC). (Photo by Toby Melville/Reuters)

People look at a Christmas tree decorated with colourful lights at a residential compound in Beijing on December 8, 2017. (Photo by Nicolas Asfouri/AFP Photo)

A zoo staff feeds crocodiles as visitors look on at the Malabon Zoo in Malabon City, north of Manila, Philippines 21 December 2017. Wearing Santa Claus hats for the upcoming Christmas season, owner Manny Tangco (R, holding megaphone) and some select animals gave visitors a tour of the 28-year-old zoo. (Photo by Rolex Dela Pena/EPA/EFE)

Open jaws of a Great White Shark Carcharodon Carcharias, South Africa. (Photo by Stephen Frink Collection/Alamy Stock Photo)