Transparency is indispensable to good governance. In China opaque smog is often a symbolic reminder of lack of transparency on matters that are the legitimate concern of ordinary folk. Hazardous air pollution has been a case in point. It has been a dirty, open secret, in the sense that official information on air quality has failed to reflect, in a timely and accurate way, what people see, sense and breathe.
Thankfully, that has just changed for the better with the introduction of real-time air-quality readings that are measured against tougher standards introduced recently.
The new standards include PM2.5 - microscopic particles linked to respiratory diseases. More than two dozen cities have begun updating daily PM2.5 readings recently, including Beijing and Guangzhou, that have been providing real-time data on a trial basis.
But Tuesday was the first time that the 74 biggest cities - mostly municipalities, provincial capitals and commercial hubs in the Pearl and Yangtze river deltas - published hourly and daily pollution readings on government websites.
The result, counting 45 cites that continued to provide only daily readings, was that only five out of 120 reported "blue-sky" days - a mainland government tally hitherto widely criticised as glossing over the truth about pollution. The adoption of the new standards signals the end of this controversial benchmark.
According to the Ministry for Environmental Protection website, Tuesday's data showed that most cities, including Beijing, reported "moderate" levels of pollution.
Yizhuang in the south reported a daily PM2.5 reading of 153, worrying but still regarded as moderate, while several cities near the capital reported the worst overall pollution in the country.
That said, the revised air-quality standards still lag behind World Health Organisation recommendations, and there remains public concern over the quality of monitoring data. This has prompted the environmental ministry to promise to combat interference by local governments with pollution readings to cover up bad news.
Greater transparency and wider monitoring keeps the public up to date with the environmental and health cost of rapid industrialisation and urbanisation.
This is a welcome development that will add momentum to calls for a more sustainable model of economic growth.