Beijing (AsiaNews/Agencies) – Beijing has declared the results of partial 4 day traffic ban a “success”. But smog continued to block the sun while other sources remain critical.

To those who claimed that there was “the usual smog” Du Shaozhong , deputy director of the Beijing Environmental Protection Bureau, replied that “human perception is not accurate” and that the reading from a sophisticated monitoring network did show a solid improvement in the city's air quality over the course of the trial. Du also reported across-the-board drops in nitrogen oxide, carbon monoxide and sulphur dioxide, between 15 and 20% and that the weekend's air quality met the safety criteria for a marathon. He added that with pollutants often circulated between cities, air pollution is “not merely a local problem”, that co-operation is needed from neighbouring cities.

But independent reports said that the government's own statistics showed the air quality over the four days rated among the top 10 worst days of the month so far - slightly worse that the same period in August 2006. They maintain that the initiative is more a publicity stunt than meaningful, given that said a stubborn gray haze shrouded Beijing throughout the test period, which couldn’t possibly be dispersed without the aid of Southerly winds and that a longer test period is needed.

Air pollution is worrying the International Olympic Committee, which just two weeks ago proposed to move some of the outdoor endurance events.  Between August 17th and 20th Beijing banned the circulation of 1.3 million over the 3 million vehicles which traffic the city’s streets each day, a move it will repeat for the duration of the Games.  Despite this, foreign cyclists who participated in a pre-Olympic trial in Beijing this weekend complained of respiratory difficulties when race passed through the city centre.  According to the Ministry for Public Safety over 18 million people live in Beijing, 12 million of who are registered residents and 5.1 million migrants.