Zhong said people working outdoors should wear masks in serious air pollution and traffic police should be allowed to wear masks in these circumstances, which can be included in protective regulations.

Air pollution is a grave issue for people working outdoors, especially in large Chinese cities, Zhong said.

Up to 40 percent of traffic police were found to have nasitis and 23 percent have pharyngitis, 33 percent to over 50 percent higher than the ratios for the general population, according to statistics, he said.

On smoggy days, patient numbers, especially patients suffering respiratory diseases, increase markedly, said Zeng Mian, director of the medical intensive care unit of No 1 Hospital Affiliated to Sun Yat-sen University in Guangzhou and a specialist in respiratory diseases.

Zeng has seen cases of co-workers having their own respiratory conditions improve when traveling in foreign countries, such as the United States, Australia and South Korea, but worsening back in Guangzhou.

The worst smog in decades has hit many parts of China this year.

Smog covered 1.43 million square kilometers on Tuesday, including Beijing and Tianjin municipalities, and the provinces of Hebei, Henan, Shandong, Jiangsu, Anhui, Hubei and Hunan, according to the Ministry of Environmental Protection.

As of 10 am Wednesday, PM 2.5 was still the main pollutant in Beijing, with an average reading of 310 micrograms per cubic meter over the past 24 hours.

The Chinese Academy of Sciences estimated that the recent smog across China has affected more than 800 million people, China Central Television reported on Thursday.

"Great efforts are needed, in every possible way, to improve the basic living environment of human beings," Zhong said.