Eight large factories in Guangzhou, including the Guangzhou branch of Sinopec and the Guangzhou Paper Group, have been ordered to finish installing anti-sulfur equipment by 2010.

The requirement is included in an air pollution reduction scheme that will run through 2010, according to the government information office.

The scheme aims to combat the presence of smog both to clean the city and to ensure the 2010 Asian Games take place in a clean environment.

The Pearl River Delta experienced 140 haze days last year, topping the whole country, Ding Zhongli, an academic working for the Chinese Academy of Sciences, said.

Chen Weiqiu, an official with the Guangzhou government's information office, said the municipal government had ordered officials to push companies and factories to take steps to clean up the city.

Another 17 medium-sized factories will have to improve their waste gas emission systems by the end of this year.

The government will install pollution surveillance systems in polluted factories in this June.

The factories will be subject to random unannounced inspections by environment-protection watchdogs.

"We have purchased advanced sulfur-capturing equipment from the United States, Norway and Austria in the past few years, so we are confident we will meet the deadline," an official with the Guangzhou Paper Group who declined to give his name said Thursday.

Waste gas emitted from restaurants is another major source of air pollution. Some 224 restaurants have received orders to cut waste gas emissions by June.

Rainfall is very abundant in the delta.

Ding said that though precipitation clears the air, it also leads some people to underestimate the scale of the problem.

The Chinese Academy of Sciences has set up an environmental pollution study and control center in the delta. At the center's opening ceremony last Thursday, director Peng Ping'an said combating the air pollution can be difficult because polluting matter flows in the air and transfers to other places very quickly.

Environment officials hope such measures will ensure a successful Asian Games.

Zhong Nanshan, a medical expert, said: "We cannot let athletes come down with asthma during the 2010 Asian Games."

Scientists have yet to determine what causes the haze, but suspended particles are commonly said to cause smog, Peng said.

(China Daily April 18, 2008)