China's air and surface water quality improved from January to April, according to a report issued by China's Ministry of Ecology and Environment on May 18.

Surface water quality is divided into five classes, with Class I being the best. The report showed that 81.2 percent of the surface water quality was graded Class I to III (good water quality), an increase of 6.3 percent compared to last year. Class V fell by 4.1 percent year-on-year to 1.4 percent. And the main pollution indexes are chemical oxygen demand, total phosphorus and permanganate.

According to the report, the average number of good air quality in 337 cities at and above the prefecture-level reached 84.8 percent. Among all the cities, Haikou city in Hainan province, Lhasa city in Tibet, and Lishui city in Zhejiang province were the top three for air quality.