Beijing, July 17 (IANS): The air quality in 338 Chinese cities showed improvements in the first half of this year, the Ministry of Environmental Protection said on Sunday.

Beijing, Tianjin and 11 main cities in China's Hebei province, an industrial zone troubled by air pollution, saw cleaner skies with about 57.4 per cent of the January-June period having "good air quality", 11 percentage points higher than the first half of 2015, Xinhua news agency quoted Luo Yi, head of the ministry's environment monitoring division, as saying.

In Beijing, the rate was 58.8 per cent, an year-on-year increase of 10.2 percentage points, while the density of PM2.5, fine particulate matter causing smog, stood at 64 mg on average, down 17.9 per cent year on year.

However, six out of the 10 cities with the worst air quality were still in Hebei.

The top 10 cities with the cleanest air were mostly along the southeast coast, except Lhasa in Tibet.

The 25 cities along the Yangtze River Delta recorded 72.9 per cent of days with good air quality, an year-on-year increase of 3.8 percentage points, while the ratio in nine cities along the Pearl River Delta was 94.7 per cent, an increase of 4.1 points.

Meanwhile, according to Luo, the country's surface water quality remained stable.

The Yangtze and Pearl rivers fell in the clean category while the Yellow river was slightly polluted. Tianjin's Haihe river was heavily polluted.

Five of the 106 lakes under monitoring were at a moderate level of eutrophication and 15 were at a light level, which roused concerns of pollution, Luo said.