Pollution levels in many Chinese cities improved last year, as the quality of the overall environment remained "stable," according to a survey released Monday by the Ministry of Environmental Protection.

Figures show that an average 66.7 percent of the days last year in 655 cities surveyed saw fair and good levels of air quality, and water quality in 89.84 percent of urban groundwater areas reached acceptable standards, up 4.44 percentage points year on year.

Also, more than 63 percent of domestic sewage in urban areas was properly disposed of last year, up 8.03 percentage points year on year. Further, some 72 percent of urban garbage was treated, up 1.04 percentage points.

However, the survey also noted 14 cities where pollution levels left much to be desired.

These cities include Taiyuan, capital of north China's coal-rich Shanxi Province, due to its poor water quality, and Urumqi, capital of northwestern Xinjiang Uygur Autonomous Region, noted for only having "slight" improvements in traffic noise pollution.

In addition, some 77.26 percent of China's urban population was satisfied with their cities' environmental protection work, according to the survey.

As one of the latest pollution control regulations, the ministry issued a draft guideline in September requiring listed companies in 16 heavily polluting industries, including thermal power generation, steel- and cement-making business, to annually publish information about their polluting emissions as well as the management of their companies' impact on the local environment.

According to the draft, any listed company that is punished, fined, suspended or shut down by the authorities for environmental violations must inform investors of these violations, punishment and remedy measures within one day upon receiving the penalty.