CHINA ACTION TO END SMOG THREAT

The city remained shrouded in a heavy haze on Monday, among the worst seen this month, despite a series of drastic controls brought in a week ago that included taking half the city's 3.3 million vehicles off the roads, closing factories and halting most building.

The city's air quality has been a huge source of concern for Olympic organisers. The games, which will bring 10,500 athletes and hundreds of thousands of spectators to Beijing, open on August 8.

A senior environmental engineer told the official English-language China Daily today: "We will implement an emergency plan ... 48 hours in advance ... if the air quality deteriorates during games." Another suggested up to 90% of the cars could be taken off the road if needed.

Beijing's air pollution index in the last four days has failed to meet the national standard for "good" air quality, rising above 100, which means the air was "unhealthy for sensitive groups."

Visibility throughout the city was reduced to several hundred yards , with high-rise buildings reduced to ghostly outlines. A day earlier, during the opening ceremony of the Athletes' Village, the housing complex was invisible from the nearby main Olympic Green.

Soaring temperatures of about 32C, 70% humidity and little wind, have helped create a soupy mix of harmful chemicals, particles and water vapour.

Du Shaozhong, deputy director of the Beijing Environmental Protection Bureau, defended anti-pollution efforts, saying the low visibility did not necessarily mean the air quality was bad.

"If it looks foggy, it has something to do with the climate as well as pollution.

"From what we've done and the measures we are taking, we can guarantee the air would be good during the games. The IOC has given their judgment that the air quality will be up to par," he said