Heavy fog has shrouded the capital city, causing a surge in the numbers of patients with respiratory problems, while Beijing Meteorological Bureau (BMB) issued four yellow alerts for dense fog in the last two days.
BMB forecasts the fog will continue on into the week, and doctors have advised caution when undertaking outdoor exercise.
"We saw a 13 percent rise in the patients who have respiratory problems from Saturday to Monday compared to the same time last week, as well as a 14 percent increase in people with strokes," said Li Jianren, the spokesman for the 120 mergency medical center.
"But there has been a 13 percent decrease in traffic accidents, probably because more people chose not to go outside," Li noted.
The 999 Emergency Rescue Center also said Monday there had been a 30 percent spike in the number of patients treated for respiratory problems, including asthma, bronchitis, and pneumonia.
According to the Beijing Municipal Environmental Protection Bureau's guidelines, the Air Pollution Index (API) Monday was between 150 to 170, indicating "slight" pollution, and the API will be lower today, between 110 to 130.
The bureau said Monday that there were nine days in October with "air quality exceeding the standard."
It added that up to Monday, there were 239 "blue sky days" this year with good air quality, seven days less than the same time last year.
However, a microblog post from Zheng Yuanjie, a famous writer, captioned his picture of the Beijing sky with "the air smells like sulfur perfume, as the capital city currently looks like a poisonous huge gas can," questioning the bureau's description of "slight" pollution in the capital.
"The fog has not been conducive for pollutants to disperse, and people who have respiratory problems should not take exercise in the morning," said Tong Zhaohui, a doctor at Chaoyang Hospital.
"Actually all people should avoid unnecessary 'outdoor activities' under such weather," Tong added.
BMB issued a yellow alert at 10 am Monday, following three previous alerts on Sunday, warning that the fog and haze could decrease visibility to within 1,000 meters in the city. In some areas, visibility was less than 200 meters.
Up to Sunday night, 163 flights at Beijing Capital International Airport were canceled, but visibility improved to 1,500 meters Monday morning, so that flights were on schedule, according to airport authorities.
The bureau forecasts dense fog will remain, gradually dissipating overnight, but the sky will not clear until the weekend.