BEIJING, Jan. 25 -- China saw its air and water quality gradually improve last year amid the country's constant efforts to fight pollution and sustain green development, official data showed on Thursday.

In 2023, the average density of PM2.5 in 339 Chinese cities at and above prefecture-level stood at 30 micrograms per cubic meter, better than the annual target of 32.9 micrograms per cubic meter and down 16.7 percent from the 2019 level, according to the Ministry of Ecology and Environment.

The proportion of days with good air quality in these cities came in at 85.5 percent last year, the data revealed.

The data also showed that 89.4 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 1.5 percentage points year on year. The share of surface water below Grade V, the lowest level, remained unchanged at 0.7 percent.

The Yangtze River and the Yellow River, two major rivers in China, saw sound water quality in 2023, with their surface water quality at Grade II.

China's ecological environment improved steadily in 2023 despite multiple sources of pressure, including unfavorable weather conditions, Minister of Ecology and Environment Huang Runqiu said at the national ecological protection work conference held earlier this week.

For 2024, Huang urged efforts to promote clean energy heating in northern China in accordance with local conditions, facilitate low-carbon transition in the high-emission steel, cement and coal sectors, and address pollution related to diesel-powered trucks, among other measures.