Tourists visit the area around National Stadium, also known as the Bird's Nest, on a smoggy day in Beijing, Oct. 14, 2018. Serious air pollution was reported in Beijing on Sunday. (Photo: China News Service/Liu Guanguan)
Tourists visit the area around National Stadium, also known as the Bird's Nest, on a smoggy day in Beijing, Oct. 14, 2018. Serious air pollution was reported in Beijing on Sunday. (Photo: China News Service/Liu Guanguan)
Tourists visit the area around National Stadium, also known as the Bird's Nest, on a smoggy day in Beijing, Oct. 14, 2018. Serious air pollution was reported in Beijing on Sunday. (Photo: China News Service/Liu Guanguan)
Tourists visit the area around National Stadium, also known as the Bird's Nest, on a smoggy day in Beijing, Oct. 14, 2018. Serious air pollution was reported in Beijing on Sunday. (Photo: China News Service/Liu Guanguan)