BEIJING -- The blue bright sky Beijing enjoyed over the past days had been mistaken by some foreign journalists as "a result of government intervention" to polish the city's image while a significant congress of the Communist Party of China (CPC) was going on.

Beijing Vice Major Liu Jingmin, a delegate to the five-yearly Party congress, said at a news conference on Friday it actually was the wind coming down from the north that cleaned the air in the host city of the 2008 Beijing Olympic Games. "Frankly speaking, we didn't take any measures. It's the weather that played the role, " he said.

But with a longer view of the city's environment and air quality, the improvement is explicit. In 2006, Beijing registered 240 "blue sky" days, or days with fairly good air quality, a rise of 64 days from the previous year.

In September "blue sky" days totaled 25, setting a record high in seven years, the latest figures from local environment authorities revealed.

Liu, also executive vice president of the Beijing Organizing Committee for the 2008 Olympic Games, said Beijing would materialize its promise of "Green Olympics" by not only improving the city's ecology and environment, but also adopting a "green", environment-friendly, approach to manage city affairs.

In one move, the municipal government has called on local residents to take public transport more instead of driving private cars through axing bus and subway fares, hoping to reduce the pollution from automobile exhaust.

Citizens who possess vehicles such as motorcycles, passenger cars, sedans and trucks have been taxed more as of October 1, with the rates ranging from 200 yuan (US$26.7) to 600 yuan (US$80) a year, almost doubling the sums before the change.

Liu said that renewable energy has been widely used in the of Olympic projects. For instance, the residences of athletes in the Olympic Village will be installed with special heating and refrigerating facilities powered by energy tapped from a neighboring sewage disposal plant.

Photovoltaic technology based on solar energy is widely used in the competition venues. And the city's first wind power plant has been set up in the north.

Liu said that the International Olympic Committee will launch regular inspections to verify whether the city has honored its commitments for a "Green Olympiad".

Over the past several years, the city has moved 167 pollutive factories to the suburbs or remoter areas. At the same time of the removal, they have undergone technical innovations, Liu said.

The city used to have 16,000 coal-consuming boilers, which spewed a large amount of dust and carbon monoxide. Now 15,000 of them have been upgraded to use clean energy forms.

Liu said that even restaurants, hotels and sponsors for the 2008 Olympics have been required to sign letters of commitment on environmental protection and energy conservation.

The government also encourages the audience to take public transport or ride bicycles to competition venues, and the buses must meet environmental standards.

To remedy its clogging traffic, the city is considering traffic restrictions during the period of Olympics, in which vehicles with even- and odd-numbered license plates, excluding taxis, buses and emergency vehicles, will be told to stay off the roads on alternate dates.

During a four-day test of the traffic ban between August 17 and 20, about 1.3 million cars were barred from the city roads each day and the amount of pollutants discharged was cut by 5,815.2 tons, figures from local authorities revealed.