BEIJING -- A Beijing Olympics official said here Monday that athletes, officials and spectators will have good air quality during the Games thanks to the pollution control measures in the past decade.

Being asked the reason for low visibility on Monday, Sun Weide, a media official with the Beijing Organizing Committee of the 29th Olympic Games (BOCOG), said he learnt from the city's meteorological administration that the air quality was grade two with pollution index under 100.

It was the high humidity, a natural phenomenon, that reduced visibility.

Beijing took more than 200 measures to improve air quality in the past ten years, Sun added.

More clean energy, such as natural gas, has been used, Sun said.

In 1998, Beijing citizens used merely 300 million cubic meters of natural gas, while the figure rose to 4.7 billion cubic meters last year.

Since March 1, Beijing has adopted the same automobile emission standard just as the EU countries do.

And the city has replaced 50,000 taxis and 10,000 buses with environment-friendly vehicles.

More than 200 heavily polluted enterprises have been moved away or suspended production, Sun added.

In 1998 when Beijing started to monitor air quality, the number of days with good air quality was only 100.

The figure reached 246 in 2007, he said.

In July, the city took more stringent measures to control air pollution and the measures were proved effective.

The concentration of carbon monoxide reduced by 15 percent from the same period last year, while nitrogen dioxide down 27 percent and particulate matters down 24 percent, he said.

This year, the air quality of 149 days was rated as good.

"Based on the measures taken in the ten years, we have full confidence of providing good air quality during the Beijing Olympic Games," the official said.