China observed less acid rain in the first half of this year, according to a communique released by the Ministry of Environmental Protection on Monday.

Of 470 cities nationwide that observe precipitation, 164 have been affected by acid rain, and acid rain cities with average PH value of rainfall lower than 5.6 dropped by 4.5 percent year on year, said the communique on environmental condition in the first half of 2015.

The total area of regions with acid rain accounted for 7.6 percent of the country's land area, which decreased by 2.4 percentage points year on year, according to the communique.

Acid rain is mainly detected in the south of the middle and lower reaches of Yangtze River, the southwestern part of Chongqing, the Yangtze River Delta and the Pearl River Delta.

The two delta regions refer to the economically-developed eastern and southern areas encompassing Shanghai and Guangzhou respectively.

Compared with the same period last year, the Beijing-Tianjin-Hebei region, the Yangtze River Delta region and the Pearl River Delta region all witnessed improved air quality, said the communique.

Six Hebei cities were featured on a list of the 10 most polluted Chinese cities.

Authorities also conducted surface water quality tests at 956 monitoring points.

Only 2.7 percent of the monitored sites reached "excellent" water quality, dropping by 1.1 percentage points year on year, while 17 percent of them had "poor" or "extremely poor" water quality, said Luo Yi, head of the environmental monitoring division with the ministry.