Beijing's smog is back year after Olympics

One year after staging a mostly pollution-free Olympics, Beijing has seen its skies shrouded in haze again, highlighting what observers call a mixed Olympic legacy on the environment.

Amid fears the city's chronic smog could damage athlete's health, Beijing took drastic steps to prevent that last August, moving or cleaning up polluting factories, curbing traffic, and ordering a halt to all construction work.

State-of-the-art facilities like the "Bird's Nest" Olympic stadium and "Water Cube" aquatic centre showcased the latest in energy-efficient design, and hopes were raised the "green" push would spread beyond the capital.

"All of the steps Beijing took to stage the Games have undeniably had a long-term positive impact on the city's environment," said Wei Fusheng, former chief engineer at the China National Environmental Monitoring Centre.

"The biggest and clearest impact has been an improvement in pollution levels."

But while few dispute that things have improved, data illustrates just how far Beijing still has to go.

An air quality index published on social networking site Twitter by the US embassy -- set up as an alternative to official Chinese data widely criticised as downplaying pollution -- has catalogued near-daily "unhealthy" readings in recent months.

Just last week, as the anniversary neared, the embassy's US-standard readings spiked to "hazardous" as a familiar choking pall settled on the city.

Touting a "Green Olympics" no doubt helped solidify environmentalism on the city's and nation's agenda but the follow-through has left much to be desired, said Greenpeace China climate and energy campaigner Yang Ailun.

"It changed the public mentality and made people remember the clear days we had 20 years ago and wonder why can't we have that again. That's a big achievement," said Yang.

However, the fact that China had to basically shut down much of the city of 18 million to meet its Olympic clean-air promises, showed that little real progress has been made.

"The Beijing experience did not provide any examples of cost-effective policies that can actually deliver results. All the major measures taken by the city were expensive and not easily replicated elsewhere," she said.

"So from that standpoint, I don't think the Olympics were that successful."

Beijing is no doubt better off a year after the Games, observers agree.

Long-term benefits are expected from the curbs on factory pollution and the Olympics-linked completion of new subway lines.

In addition, Beijing has maintained some driving restrictions that, while less stringent than those during the Games, still keep hundreds of thousands of the city's more than three million vehicles off the roads each day.

But with 1,500 new cars added to the mix daily, those measures may soon be overwhelmed, warn experts.

"These steps don't change the fact that this city is still developing at a fast rate," said Greenpeace's Yang.

The city government touts data that it says show dramatically improved air quality during and since the Olympics but some experts have said weather and even the slowing economy might also have played significant roles.

And questions continue to surround Beijing's data, especially the particulate matter emitted largely by motor vehicles.

When the US embassy data flags "hazardous" smog, Beijing's own official pollution index rates it as "slightly polluted", due mainly to the fact that Beijing measures large particulate matter.

The embassy's US standards, however, measure much smaller particles that are more easily inhaled and pose a greater health threat.

The Beijing Environmental Protection Bureau declined to respond to AFP requests for comment, except to issue a statement saying: "Our figures show air quality in the first half of the year and in July was better than last year."

And while Beijing officials are quick to stress that its own particulate readings are among the best in a decade as a result of the Olympics measures, they remain several times higher than World Health Organization standards.