Beijing and its surrounding areas suffered serious air pollution in the first six months of this year, with two out of three days failing to meet standards, an official report released by the Ministry of Environmental Protection (MEP) showed Wednesday.

The report, which recorded air quality readings in 74 cities and three key regions, came amid expectations for the release of an action plan to improve air quality for the next five years, which reportedly will set targets for the control of major pollutants.

According to the MEP, combined average air quality readings for the 74 cities met standards for just over half of the days during the January to June period.

But Beijing and its neighboring Hebei Province and the city of Tianjin experienced poor air quality for more than two-thirds of the days during the same period, with over one-quarter of the first half being heavily polluted.

In comparison, the Yangtze River Delta region saw reasonable air in more than half of the time, and the Pearl River Delta region enjoyed 80 percent of pollution-free days.

"The huge gap in terms of air quality readings between Beijing and eastern and southern cities is mainly caused by climate difference. Those cities are much nearer to the sea and the sea wind will dilute the pollution," Zhao Zhangyuan, a research fellow with the Chinese Research Academy of Environmental Sciences, told the Global Times Wednesday.

According to the MEP report, prime pollutants for Beijing and its surrounding areas are PM2.5, airborne particles measuring less than 2.5 microns in diameter, and ozone.

The average level of PM2.5 for the 74 cities in the first half was 76 micrograms per cubic meter, more than double the regulated standard. The readings in Beijing and its surrounding areas reached 115 micrograms per cubic meter, with no single city meeting the standard.

"The existence of too many thermal power plants and facilities for waste burning around Beijing hiked the PM2.5 readings, while the ozone, which comes from a series of reactions of nitrogen oxides, is the major by-product of vehicle emissions," Zhao said, adding that coal-fired heating in winter should also be blamed for poor air quality.

The State Council in mid-June rolled out a series of measures to curb the pollutants.

An action plan to improve air quality during the 2013-17 period is expected to be released early August.

The 21st Century Business Herald quoted sources as saying that the new action plan will complement an earlier plan released late in 2012, which was "too conservative" in tackling air pollution, and specific targets will be set for the control of PM2.5 in the three key regions.

Many regions have set their own targets for the fight. An insider told the 21st Century Business Herald Beijing aims to control PM2.5 level around 60 micrograms per cubic meter by 2017, a reduction of over one-quarter compared with the 2012 level.

Meanwhile, the Beijing News reported that the action plan will bring an investment of 1.7 trillion yuan ($277 billion) to the improvement of air quality.

"These actions are helpful to improve the air. But a practical provincial cooperation is needed in dealing with this kind of matters because it is never an issue for a single local government," Zhao told the Global Times, adding that such cooperation has also been appealed for before, to little effect.