Air pollution has turned into a major hazard affecting urban residents' quality of life.

Air monitoring in 522 cities across the nation last year found that 39.7 percent of them had either medium or serious air pollution, which poses a potential threat to residents' health.

Emissions from car exhausts have been found to be one of the major sources of urban air pollution.

Our cities are currently home to around 31 million cars, whose exhausts poison the air we breathe every day.

State Environmental Protection Administration (SEPA) Director Zhou Shengxian has warned that, unless standards for car exhaust emission are further raised and the quality of the petrol they use is further improved, harmful substances emitted from motor vehicles will double over the next 10 years.

Although SEPA said that it would try its best to gradually raise the car emission standards for new vehicles and draw up rules to get off the road old ones whose exhaust emissions fail to reach the required standard, we have no reason to be optimistic about the improvement of urban air quality.

We all know that exhaust emissions are at their most serious when cars cannot run at an even speed. Yet, crowded as traffic currently is in most urban areas, it is almost impossible for motor vehicles to run at an even speed. Therefore, exhaust emissions will get even worse.

More and more Chinese people are getting behind the wheel, with car ownership likely to double or treble in the coming decade, a trend which will be accompanied by more and more traffic jams in our cities.

In these circumstances, it is doubtful whether raised emission standards for motor vehicles will make a difference.

Another major contributor to urban air pollution is sulphur dioxide, primarily from the burning of coal.

SEPA is said to have signed agreements with major power companies and will do the same with local governments on cutting sulphur dioxide discharges from thermo power generation.

The country has failed to bring sulphur dioxide discharges down to the level required in the 10th Five-Year Plan period (2001-05). The total amount emitted was 25.49 million tons in 2005, 7.49 million tons more than the required amount, an increase of 27 percent compared to 2000.

Sulphur dioxide discharges are expected to be reduced by 10 percent during the period of the 11th Five-Year Plan (2006-10).

Whether the promises made by power companies and local governments will make a difference depends on how much money they will invest in the renovation of their facilities to get rid of the sulphur from the coal they use.

As the national environmental watchdog, SEPA needs to take harsh measures to make sure these firms and local governments keep their promises.

(China Daily June 1, 2006)