Air pollution in Beijing

BEIJING, CHINA - MARCH 22: Xiwen Qing, 26 years old, from Gansu Province poses for a portrait at Houhai Nanyan in Beijing, China on March 22, 2017. Heavy smog has become a major environmental issue in China, with Beijing being subject to frequent air pollution that exceeds safety limits. China was ranked as the leading carbon dioxide emissions producer in 2014, followed by the United States. China declared a "war" on pollution recent years amid increasing public concern over the environment and health impacts. Due to rapid development and industrialization, many of the country's biggest cities rank among the most polluted urban centers in the world. (Photo by Andrea Verdelli/Anadolu Agency/Getty Images)