The head of China's environmental watchdog said on Tuesday that China has made positive progress in environmental protection in the past five years but still faces an arduous task.

Minister of Environmental Protection Zhou Shengxian made the remarks at a bimonthly session of the Standing Committee of National People's Congress, China's top legislature.

Zhou said that China's efforts in environmental protection should be acknowledged for outstanding performances in pollutant emissions reduction, waste water treatment and afforestation.

Chemical oxygen demand (COD) and sulfur dioxide emissions in 2010 dropped 12.45 percent and 14.29 percent, respectively, compared to 2005, and continued on a downward trend in the first half of this year, Zhou said.

Meanwhile, oxynitride emissions rose by 6.17 percent in the first half of this year, he added.

The annual concentration of sulfur dioxide and particulate matter in urban air fell by 26.3 percent and 12 percent, respectively, compared to five years ago.

During the past five years, China closed a large number of thermal power stations with a total generating capacity of 76.83 million kilowatts, and established 2,832 waste water treatment plants.

Zhou said the treatment rate of urban waste water increased to 77 percent, up from 52 percent in 2005, but he also said that 29 percent of Chinese cities lack household garbage treatment facilities.

To put economic development in line with environmental protection, China canceled the export rebate for more than 200 kinds of products with high environmental risks, and stopped lending for projects not in accordance with environmental protection rules.

The average emissions of newly-produced cars in 2010 decreased by 90 percent from that of 2000, thanks to strict "pollution-free" rules for the production of new kinds of cars and government subsidies put toward eliminating old, non-environmentally-friendly cars.

Moreover, Zhou said China has established 31 storage facilities for waste produced by its current 13 nuclear power generating units, and formed a national monitoring and warning network for nuclear radiation, which he said played a role in handling radiation from Japan's crippled reactor earlier this year.

Currently, 28 nuclear power generating units are under construction, said Zhou, indicating increasing pressure for preventing radiation risks.

Forest acreage reached 20.36 percent, and China now has 2,588 natural reserves covering 14.9 percent of the country's territory.

Zhou said China also strengthened law enforcement in the past five years and closed more than 7,000 companies which "did harmful things" to the environment.

Despite the improvement, Zhou said environmental pollution is still very serious, and China is facing an arduous task in emissions reduction.

Nearly 10 million hectares of farmland have been polluted, and more than 133,000 hectares of land are occupied or destroyed by solid wastes, Zhou said.

In the first eight months of this year, 11 accidents involving heavy metal pollution occurred, including 9 accidents that resulted in local residents suffering from the effects of high levels of lead in their bloodstreams.

The situation is especially severe in rural areas because of the over-exploitation of water resources, arbitrary emissions of waste water and the abuse of fertilizers and pesticides.

Over the next five years, Zhou said China will continue to improve pollution treatment in major water basins and seas, while constantly improving policies and rules concerning environmental protection.

He promised to resolve environmental problems affecting people's health, make the system that takes pollution emission achievements into account when assessing of the work of local governments more strict, and further promote the use of clean energy.

"We will ensure the realization of the goal of gross emissions of major pollutants, and enhance the role of environmental improvement in driving China's transformation of its economic growth mode," said Zhou.