Most Chinese cities are not coming clean on smog: survey

Despite some recent progress in Beijing and other big cities, most mainland cities have still not made a sincere effort to improve transparency about their air pollution problems, according to a study.

The Institute of Public and Environmental Affairs' survey of 113 cities found 78, including many provincial capitals and major industrial hubs, had yet to release information on fine airborne particulate, such as PM2.5.

Increasing concern about PM 2.5 - particles matter less than 2.5 micrometres in diameter which, because they are so fine, can lodge deep in the lungs - spurred a national outcry at the government secrecy surrounding smog problems.

That led to a major overhaul of outdated clean-air standards.

"This is a reality check," said Ma Jun , director of the Beijing-based institute. "We've seen some breakthroughs in Beijing and Guangdong as a result of the stricter pollution limits, but we also clearly see a widening gap between different regions."

Of the 55 cities that began to publish PM2.5 readings this year, Beijing and some Pearl River Delta cities ranked best owing to their strides in disclosing PM2.5 data and giving ample, up-to-the-hour information from dozens of monitoring stations.