BEIJING, Nov. 21 (Xinhua) -- China's air and water quality improved over the past 10 months, said a report issued by China's Ministry of Ecology and Environment.

The report showed that 81.8 percent of surface water was graded Class I to III (good quality) in the first 10 months, up 6.4 percentage points from the same period last year, while Class V water fell 2.4 percentage points year on year to 0.8 percent.

Surface water quality in China is divided into five classes, with Class I being the best.

For major rivers, including the Yangtze and Yellow rivers, 86.7 percent of the water quality was graded Class I to III in October, up 6.4 percentage points year on year, and 0.4 percent was graded Class V, down 1.7 percentage points year on year.

The percentage of days with good air quality was 87.7 in 337 cities at and above the prefecture-level from January to October, up 5.5 percentage points year on year. The average concentration of PM2.5 (atmospheric particulate matter) was 30 micrograms per cubic meter in the January-October period, down 11.8 percent year on year.

Among the cities, Haikou in Hainan Province, Lhasa in Tibet Autonomous Region and Zhuhai in Guangdong Province ranked as the top three for good air quality in the past 10 months.