BEIJING, Oct. 10-- The dense haze continued in Beijing and neighboring areas for a third day on Friday with a yellow alert remaining in effect.

The first bout of heavy smog this autumn has forced authorities in Beijing and Hebei Province to cut industrial production and suspend construction work. Tianjin Municipality and Henan Province have also issued haze alerts.

Thirty-five companies have halted production and 74 others reduced emissions by 30 percent in the capital, said the Beijing Municipal Commission of Economy and Information Technology on Friday.

The air quality index (AQI) for Xingtai City in Hebei was 500 on Friday morning, making it the worst polluted city, again. Xingtai, an industrial city 400 km south to Beijing with heavy industries such as coking, glass and steel,just shook off the title of the country's worst polluted city in July and August.

Within a 25-km radius of downtown Xingtai, there are 133 plants in iron and steel, cement, glass and power, etc. which consume 16 million tonnes of coal per year. Local officials call the polluting firms the "black necklace" of the city.

"We feel huge pressure to reduce pollution,"said Xu Huailiang, deputy head and chief engineer of Xingtai Environmental Protection Bureau. Xu, who has worked in the bureau for 30 years, says he feels ashamed whenever people talk about Xingtai as the country's worst polluted area.

The city is taking action. This year, it has cut iron and steel capacity by 1.85 million tonnes and coking capacity by 1 million tonnes. By 2017, the city will have cut a total of 5 million tonnes from iron and steel capacity.

Sept. 30 was set as the deadline more than 2,000 companies in the city to discharge pollutants in line with environmental protection requirements or be closed down.

"The pollution situation is grave, but we have a firm resolve to deal with it," said Xu, adding environmental officials are checking whether companies have met the targets.

The Beijing, Tianjin and Hebei region has been listed as the worst polluted region by the top environmental watchdog. Coal burning, vehicle exhausts and dust are among the major pollutants.

In February, the coordinated development of the region became a national strategy, with the joint treatment of air pollution as one of the main purposes.

"The haze in the region in recent years, is not only a problem for the region itself, but one related to all northern and eastern regions," said Zhang Gui, deputy director for Beijing-Tianjin-Hebei Development Center at Hebei University of Technology.

"The pollution is a result of a growth model featuring high energy consumption and emissions. It must be solved on a regional level," said Zhang.

Results of pollution control in the region are already felt. Take Xingtai City. The city has seen 66 days with good or fairly good air quality this year, 28 days more than the whole of last year.

Beijing and neighbors regularly coordinate on pollution, but they need to improve their information sharing and consultation on alerts and response, said Li Lixin, an official with the Beijing Environmental Protection Bureau.

"In terms of joint regional pollution control, each city or province should first deal with its own problems and then shoulder common responsibilities," said Feng Yinchang, a professor in environmental science and engineering at Nankai University in Tianjin.

"A simple transfer of pollution should be avoided," Feng stressed. Beijing is considering moving some companies to Tianjin and Hebei as it transfers some of its non-capital functions.

China plans a monitoring and warning system to respond to heavy air pollution with more attention given to pollution control in coal burning, vehicles and dust in key regions, according to a revised draft of the Air Pollution Law unveiled in early September. More strict law enforcement is expected.

Despite slight improvements in air quality in the Beijing, Tianjin and Hebei region this year, days of heavy pollution will come again, said Feng.

"It will take a long time for us to realize the ideal blue sky days because the pollution problem will not be solved in three or five years," said Feng.