BEIJING, May 25 -- Air quality in Chinese cities improved in April amid the country's constant efforts to reduce pollution and promote green development, data from the Ministry of Ecology and Environment showed.

For the 339 cities monitored by the ministry, the proportion of days with good air quality stood at 89.8 percent last month, up 8.7 percentage points year on year, according to the ministry.

The average density of PM 2.5, a key indicator of air pollution, remained unchanged from the same period last year at 28 micrograms per cubic meter, and that of PM 10 fell 3.6 percent year on year, said the ministry.

Among the 168 key cities monitored in April by the ministry, Zhuhai, a city in south China's Guangdong Province, was at the top in terms of good air quality. It was followed by Huangshan in east China's Anhui Province and Haikou in the southern province of Hainan.