Beijing is mapping out strategies to reduce the amount of air pollution in the capital city over the next five years in its 11th five-year (2005-10) environmental protection plan.

"Beijing still has a long way to go towards reaching the environmental standards of a life-friendly city," said Du Shaozhong, deputy director of the Beijing Environmental Protection Bureau (EPB), at a news conference on Wednesday.

"The campaign against air pollution in Beijing faces an uphill battle, since the city suffers from multiple sources of pollution and has only a short amount of time to address the problem."

The gloomy smog that hung over the capital city last week was a grim reminder of how pressing the problem is.

According to the China Environmental Monitoring Centre's air-quality index, the amount of pollution in the air last Tuesday hit its worst level, scoring a "hazardous" rating for the 24-hour period ending at noon.

For several days last week, Beijing was blanketed in a heavy fog that reduced visibility to a few hundred metres and delayed at least 80 flights, according to a Xinhua News Agency report.

In the interest of protecting the city's 13 million residents from the harmful effects of air pollution, the municipal government has pledged in its environmental plan to control the release of major pollutants in the coming years.

For example, sulphur dioxide (SO2) emissions are to be cut by 20 per cent of their level last year by 2010, according to the plan.

To reach this target, Beijing will rely more on clean energy like electricity or natural gas, and gradually give up the use of coal. In central Beijing, coal combustion boilers with a capacity of less than 20 tons are to be powered by clean energy sources within the coming year.

And by 2008, the five major coal-fired power plants in Beijing are to have installed equipment to remove dust, sulphur and nitrogen from their emissions.

Beijing will also impose stricter exhaust standards on automobiles and speed up the retirement of old and inefficient buses and cars.

Studies have shown that auto exhaust is a leading cause of pollution in Beijing. Automobiles pump out 80 per cent of the carbon monoxide in the city's skies, 75 per cent of hydrocarbon, 68 per cent of nitrogen oxide and 50 per cent of the other fine particles.