Eleven Chinese cities suffered poor air quality for more than three months during the first three quarters this year, according to the country's environment watchdog.

The 11 cities, including Beijing, Lanzhou, Linfen, Urumqi and Datong, saw air pollution for more than one third of the time in the first three quarters, said a report issued Tuesday by the State Environmental Protection Administration.

Ninety percent out of the 113 major Chinese cities monitored recorded slight air pollution, and 18 percent recorded heavy air pollution.

Particulate matter was the leading pollutant, followed by sulfur dioxide and nitrogen dioxide.

Acid rain remained a serious problem, particularly in the eastern Zhejiang Province where all the cities monitored suffered from acid rain, but the administration did not give a detailed list.

The report linked increasing discharge of pollutants with the country's booming economy. China's gross domestic product (GDP) growth reached 10.9 percent in the first half of the year.

China produced more than 12 billion tons of industrial waste-water in the first half, up 2.4 percent over the same period last year.

The chemical oxygen demand (COD), a major index of water pollution, increased by 3.7 percent, and the emission of sulfur dioxide increased by 4.2 percent in the first half.

But despite severe pollution in certain areas, the report said the overall environment condition saw little change in the first 9months.

The days of air pollution in major cities in the third quarter dropped from the same period last year, said the administration.

It also said the average days with satisfactory air quality in 113 major cities accounted for 84 percent of the total time, and 66.4 percent of major cities had satisfactory air quality in 80 percent of the time.

(Xinhua News Agency November 23, 2006)