BEIJING, July 29 -- Official data showed a steady improvement in China's air and water quality in the first half of this year (H1), as the country continues to battle pollution and pursue green development.

According to the Ministry of Ecology and Environment, during the January-June period, the average density of PM2.5 in 339 Chinese cities at and above the prefecture level stood at 33 micrograms per cubic meter, down 2.9 percent year on year.

The proportion of days with good air quality in these cities during the period was 82.8 percent, up 1.4 percentage points from the same period last year.

The ministry's data also showed that 88.8 percent of monitored sections had "fairly good" surface water quality -- at or above Grade III in the country's five-tier water quality system, up 1 percentage point year on year.

The share of surface water below Grade V, the lowest level, stood at 0.8 percent, down 0.2 percentage points from a year earlier, according to the ministry.

China has steadfastly advanced its "Beautiful China" initiative, emphasizing ecological and environmental protection as a top priority in its social and economic development.

During the third plenary session of the 20th Central Committee of the Communist Party of China earlier this month, Chinese leadership pledged to "prioritize ecological protection, conserve resources and use them efficiently, and pursue green and low-carbon development."