Following economic liberalisation, China has seen an upward swing in profits and pollution. The government is now planning to expand a scheme in which factories have to pay a fee according to how much they pollute. The scheme is focussed mainly on curbing the emission of sulphur dioxide. Millions of Chinese coal-burning factories spew sulphur dioxide in the atmosphere causing smog and acid rain over large areas. At present, the companies are charged us $39.4 for each tonne of sulphur dioxide they emit. According to Hao Jiming, a professor of environmental engineering at Qinghua University in Beijing, the costs of reducing emissions with modern clean-coal technology ranges from us $197 to us $492 per tonne. "We suggest that the government collect not on the basis of emission-reduction costs, but rather at lower levels that enterprises can afford,' said Hao.