FOR a time Beijing looked like a scene from Dickensian London of the Industrial Revolution when pollution blocked out the sun and coal dust was everywhere.

On December 4 the capital city was shrouded in a dense smog that seriously disrupted city life. Tens of hundreds of flights were grounded. Road traffic was severely hampered by low visibility. People choked on the heavily polluted air invading their lungs, even though they wore face masks.

It's no longer news that Beijing was smothered by a smog of epic proportions, but this time people's reaction is markedly different.

Many people are now fuming over the government's perceived lack of transparency in releasing meaningful air-quality ratings that truly reflect their impression of the smog's gravity.

Popular outcry and scrutiny has forced the state environmental watchdog to announce that it will add to the air quality monitoring system the so-called PM2.5 particles, or airborne pollutants measuring less than 2.5 microns in diameter.

Currently only particles with a diameter of between 2.5 and 10 microns, or PM10, are reflected in the system that issues daily updates on air quality.

However, fine PM2.5 substances, usually a twentieth as thick as a human hair, are increasingly known as a serious health hazard, and public pressure is building on the Ministry of Environmental Protection (MEP) to publicize PM2.5 readings as soon as possible.

Deadly content

The MEP announcement came as a relief to people who have long inhaled filthy air yet remained unaware of its potentially deadly content.

Seasonal sandstorms besetting much of China help the spread of airborne particles. As sandstorms sweep across the coal-producing areas in northern China, they gather grit as well as soot with a high concentration of toxic heavy metals like lead and arsenic.

The government's belated decision to survey and disclose PM2.5 levels is welcome. But to the public's chagrin, that new particulate measurement standard will not be adopted nationwide until 2016.

This five-year delay is prompting speculation that the government is not taking the PM2.5's public health consequences seriously.

A widely suggested reason for this delay is that if the new gauge is employed, we'll be confronted with frightening PM2.5 readings almost every day.

But that's no reason to procrastinate, according to Zhuang Guoshun, Fudan University professor of environmental science, who has long collected air samples from around China and assessed their content, including PM2.5 components.

In an interview with Shanghai Daily, he said PM2.5 readings in Shanghai average 50 to 80 micrograms per cubic meter a year, while the World Health Organization's PM2.5 levels considered "safe" stand at 35 micrograms per cubic meter.

Following the severe fog on November 13 and 14, the latest to hit Shanghai, the city's PM2.5 levels soared to 190 to 200 microns per cubic meter, almost 5 times the WHO standard.

In fact, although Shanghai has fewer days of "haze" than Beijing, now dubbed rather euphemistically a "misty capital," its PM2.5 readings occasionally exceed those in Beijing, and PM2.5 is the major culprit of haze, said Zhang.

Shanghai cleaned up the skies for the sake of its image during the Expo last year when the city saw consecutive days of blue skies. After the show was over, the air quality quickly deteriorated.

One reason is that construction sites citywide resumed work after the Expo was over. What's more, farmers in the surrounding provinces again burned straw to clear their fields - they had been compensated by Shanghai for not doing so when the Expo was ongoing.

Burning straw and other agricultural waste is one of the main causes of haze apart from industrial emissions and dust storms, Zhang said. But even though Shanghai has closed down many of its polluting factories in recent years, the city's PM2.5 levels are still on the rise.

Car exhaust

A significant part of that increase comes from the growing number of cars on the city's roads. Their exhaust fumes, rich in sulfur dioxide and nitric oxide, form PM2.5 particles after a series of chemical reactions under air pressure.

And snarled road traffic contributes to emissions of automobile-generated PM2.5, as idling engines consume more fuel and thus discharges more exhaust, said Zhang.

He dismissed the belief that planting trees would reduce PM2.5, as these pollutants move at an altitude of several thousand meters and are extremely small in size. Trees can do little to sequester them from reaching the ground.

Worse, trees release volatile organic compounds (VOC), which after oxidization also develop into PM2.5 particles. So having more greenery will not help lower PM2.5 levels, Zhang said.

What really matters in the fight to control PM2.5 is a change of the mindset that places growth above all else, and this is what the Fudan professor has been calling for all these years.

"Growth should benefit people. When it harms their health, what's the point of growth anyway?" asked Zhang.

Zhang advocates developing public transport over private cars. Although haze and smog are sometimes meterological anomalies and increasingly a regional problem, controlling the local sources of emissions is within a city's ability, he said.

Nevertheless, it is a question whether a city is willing to demonstrate that ability. As a critic of the delayed implementation of the PM2.5 gauges, Zhang argues that China should adopt the same air quality evaluation criteria as the West. We cannot sacrifice people's health just to develop the economy, he said.

There are signs that some regions may lead the nation in having PM2.5 included in air quality ratings. Shanghai, for example, seeks to be among the first areas in adopting a stricter air quality monitoring system before it is introduced nationwide in 2016.

If that quest succeeds, it surely will be something to celebrate - not just about more accurate weather forecasts, but about a government more receptive to people's environmental concerns.

After all, as Zhang says, what we lack is not the equipment and know-how to take PM2.5 figures, but the courage to do so.