A faint view of the Arc de Triomphe through a foggy haze in Paris on March 20. French media reports state that high levels of air pollution are also affecting the atmosphere over the city. (Yoan Valat / EPA)
A view of the Eiffel Tower in Paris is almost blocked out by a haze of pollution on March 18. (Franck Fife / AFP/Getty Images)
The Sacre-Coeur Basilica and the Montmartre district are in thick smog on Feb. 12. (Patrick Kovarik / AFP/Getty Images)
A traffic sign reads “Air pollution, slow down” near Rennes, France, on March 21. (Damien Meyer / AFP/Getty Images)
The skyline of Shanghai is pictured on a hazy day on Feb. 8, 2015. (Johannes Eisele / AFP/Getty Images)
A woman wears a mask as she walks through Yuyuantan Park on a heavily polluted day in Beijing on March 7. (Mark Schiefelbein / Associated Press)
A Thai Airways International aircraft flies through polluted air over Chiang Mai, Thailand, on March 4. (Pongmanat Tasiri / EPA)
Smog envelops buildings on the outskirts of New Delhi on Nov. 25, 2014. (Roberto Schmidt / AFP/Getty Images)
Smog in Singapore on Sept. 15, 2014. (Roslan Rahman / AFP/Getty Images)
A smoggy Seoul skyline on Nov. 26, 2014. (Ed Jones / AFP/Getty Images)
Tehran’s Milad Tower is barely visible through heavy air pollution on Dec. 31, 2014. (Behrouz Mehri / AFP/Getty Images)
Visitors to Griffith Park take in a smoggy L.A. Basin on Oct. 24, 2014. (Mark Boster / Los Angeles Times)
