BEIJING - POLLUTION levels in Beijing over the past six months were the lowest seen in nearly a decade, environmental officials said on Friday.

'We can say that air quality in Beijing has already improved. We can feel that and see blue skies here,' said Mr Du Shaozhong, vice-director of the Beijing Environmental Protection Bureau.

Part of the improvement has been due to the continuation of some measures imposed during the Olympics last year, said Mr Du.

Beijing recorded 146 days this year that fall within the country's national standard for acceptable air, he said. When the air pollution index (API), which measures four major pollutants, is under 100, China considers it a 'blue sky day'.

So far this year, Beijing saw 23 more 'blue sky days' than during the same period last year, according to the environmental bureau. Meanwhile, the average pollution readings recorded for the months of January, March, April, May and June were the best since 2000.

However, the air in February was worse than last year and included one particularly smoggy day, on Feb 10, when the API hit 307 - considered hazardous for all populations by US standards. China labels such levels 'heavy pollution' and encourages people to stay inside.

The capital's polluted air underwent a massive cleanup campaign for last summer's Olympic Games. Typically, Beijing's air quality is two to three times dirtier than in most Western countries.

City officials planted thousands of acres of trees in and around the city, shut down scores of factories, stopped almost all construction and removed 2 million vehicles from the roads for a two-month period. A limited version of the traffic restrictions was continued after the games ended. -- AP