The sun rises in a blue sky in Beijing August 2, 2008. [Agencies]

The air quality in the Olympic host city has been a major concern for some athletes and media organizations, but environment officials dismissed worries about pollution during the Games.

According to the Chinese Lunar Calendar, August 7 -- a day ahead of the Games opening ceremony -- is the day when autumn officially begins.

The weather at that time was expected to be fine and it was usually the best season in Beijing, Du said last week.

More polluting businesses would be shut and more vehicles would be taken off the roads if the air quality worsened due to "extreme unfavorable weather conditions" during the Olympics and Paralympics, according to the Ministry of Environmental Protection.