Thick fog blankets Beijing, capital of China, June 28, 2013. [Wang Haixin/The Beijing Times]

Environment Minister Zhou Shengxian announced at an international forum that China will issue a series of tough measures by the end of July to curb air pollution.

The measures will enhance controls over PM2.5, or dangerous airborne particles measuring less than 2.5 microns in diameter, in populated regions and metropolises, said Zhou, who added that curbing air pollution is a "protracted battle."

Heavy pollution has hit multiples parts of China since the beginning of the year, affecting 600 million people, according to statistics from the National Development and Reform Commission.

At an environmental forum held in Guiyang, capital of southwest China's Guizhou Province, that ended on Sunday, experts said China has the worst PM2.5 readings of any country, adding that air quality in 64 percent of China's cities does not meet new national standards issued in 2012.

Ding Yihui, a climate change advisor at the China Meteorological Administration, said major cities have suffered a significant reduction in the amount of sunlight they receive since the 1980s, which has affected transportation and agriculture.

As a major air contaminant, PM 2.5 not only causes direct pollution, but also leads to secondary pollution, Zhou said.

Although government departments have strived to curb air pollution for years, their achievements have been few. Air pollution has also spread to neighboring countries.

Zhou said a government action plan for preventing and treating air pollution calls for strictly controlling sectors that produce large amounts of waste and pollution, as well as strengthening efforts to eliminate outdated technology in the steel, cement and electrolytic aluminum industries.