The air in Beijing is the cleanest it has been for a decade and city officials plan to maintain the better quality even after the Olympics, a top environment official was quoted Wednesday by state media as saying.

But it was unclear whether the authorities will continue the stringent measures adopted for the Games, including shutting down factories and enforcing no driving days for vehicles based on an alternating even-odd number system.

On nine of the past 18 days, the air in the Chinese capital was considered excellent, while on the others it was rated "fairly good", Du Shaozhong, deputy director of the Beijing environmental protection bureau was quoted by the China Daily saying.

The average daily air pollution index (API) over the 18 days was 56, far below the 81 reported for last year, he said.

"This is the best average summer API for a decade," Du said.

In July 2006, Beijing had five days of "excellent" air quality, while last August it reported just two, he said.

Beijing is committed to making blue skies the norm after the Olympics, Du said.

"Beijing will become a much more livable city," he was quoted saying. "New measures will ensure air quality continues to improve after the Games."

Details of the measures will be announced later, he said.

"But whether they relate to reducing emissions from cars or dust from building sites, the requirements will be stringent," Du said.

Despite a few days of blue skies and white clouds, however, there were many days including Wednesday when haze hung over the city, but officials had said it was not necessarily pollution.

About a third of the capital's 3.3 million vehicles have been taken off the roads as a result of the odd-even number system, not only contributing to better air, but mitigating traffic problems.

Guo Hu, director of the Beijing meteorological center, was cited as saying showers are forecast for Wednesday and Thursday, while clouds are expected for Sunday's closing ceremony.