HFC 23 is mainly emitted by production of a refrigerant and a feedstock for making non-stick pans, while nitrous oxide is emitted by nylon production.

"CDM has helped industrialized countries meet their emission target at much lower cost. At the same time, it also has played an active role in helping developing countries' development," Xie said.

"The mechanism is widely recognized as a win-win approach both for industrialized countries and developing countries and any inconsistent CDM-related policies will seriously hurt market trust and confidence."

The EU said these kinds of emission reductions should be the responsibilities of developing countries instead of being done through the carbon market.

Xie said such a statement violates the "common but differentiated responsibilities" and is aimed at making developing countries shoulder comparable responsibilities with developed countries.

The EU believes such trading restrictions may promote CDM and flow money to the least developed countries.

Xie said CDM has little to do in helping these countries get sufficient money to handle climate change.

Meanwhile, there are suspicions that some industrial gas CDM companies are encouraging emissions to maximize their carbon credits.

"As far as I know, no organization or agency has done due-diligence investigations in China before reaching such kind of conclusions," Xie said.

CDM projects have brought Chinese companies advanced management skills, including scientific greenhouse emission monitoring approach, Xie said.

Martin Hession, vice-chairman of the CDM executive board under the United Nations Framework Convention on Climate Change, said CDM's success cannot be measured simply in terms of the number of projects and credits it has delivered, but also in terms of the institutional and cultural change it has driven.

(China Daily December 9, 2010)