Chengdu, capital of southwest China's Sichuan Province, is investing billions of yuan in developing an environment-friendly pesticide and in a tree-planting scheme that will cover more than a third of the urban area.

The projects are part of a 37-billion-yuan (US$4.93 billion) plan for environmental improvements up to 2010.

The 240 projects, featuring water, air and noise pollution control as well as the environmentally-friendly disposal of waste in urban and rural areas, are aimed at improving air and water quality.

According to the city's environmental protection bureau, the investment will also be used to build a network of 10,000 monitoring points to reduce discharges of industrial pollutants into into local rivers.

Chengdu lies in the valley formed by the Minjiang and Tuojiang rivers, two tributaries of China's longest river, the Yangtze.

Eight billion yuan will be put into research and development of the pesticide as well as ten garbage treatment centers and a major afforestation project covering 10 million square meters, or 35 percent of urban Chengdu.

The city annually discharges two billion cubic meters of waste gases, 150,000 tons of dust, 20 million tons of sewage and six million tons of waste residue.

Under the plan, 90 percent of urban sewage will be treated by 2010, compared with 55 percent in 2005, environment protection officials said.

According to the local meteorological station, the city witnessed 246 days of fairly good air in the first nine months of this year, accounting for 90 percent of the total.

To improve the air quality, the city has ordered the closure of coal-burning power plants and paper-making plants with annual production capacity below 17,000 tons while enforcing environmental rules on construction sites and motor vehicle exhausts.

Meanwhile, Chengdu has built more than 20 sewage plants to improve water quality and prevent pollution in local rivers, lakes and reservoirs.