A huge amount of toxic organic compounds were found in the smog that shrouded Beijing and surrounding cities in January, chemicals that resemble those in the so-called photochemical smog a hundred years ago which killed over 800 residents in Los Angeles, a recent study showed.

Researchers at the Chinese Academy of Sciences pointed to emissions of human-made pollutants as the culprit of the toxic air pollution in the capital that has lasted for years but has gained public attention only in recent years when increasing cases of respiratory problems are reported.

Death threatening

Air quality has deteriorated so fast and pollution has expanded so extensively in China that in January as many as 1.4 million square kilometers was enveloped by hazardous dense hazes, covering most parts of northern and eastern China and affecting more than 800 million people, government data showed.

January's haze is mixture of pollutants in Los Angeles' photochemical smog in 1940-1950 and smog in London in 1952, while overlaid by dust aerosol which is unique in China, said lead researcher Wang Yuesi.

Photochemical smog is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere, which leaves airborne particles and ground-level zone. Nitrogen oxides were exactly what researchers had found in January's haze in Beijing, a major component of Los Angeles' photochemical smog in which more than 800 died.

Sources of pollution

In Beijing, motor vehicle exhaust is responsible for roughly one fourth of pollutions of small particles less than 2.5 micrometers in diameter, referred to as PM2.5, the panel ruled.

Coal plants and imported pollutants are listed as the second cause of PM2.5 pollution, with their contributions at about 20 percent for each, the study showed.

To sum up, the pollution is a "direct consequence of man-made profligate emissions and the disruption of natural ecological balance", according to the result released by the think tank.