New Delhi, Sep 25 (IANS): The Delhi Metro has been certified by the UN as the first Metro rail in the world that has helped in reducing greenhouse gas (GHG) emissions, an official statement said Sunday.

According to the UN, Delhi Metro has helped in reducing pollution levels in the city by 6.3 lakh tonnes every year, thus helping in mitigating impacts of global warming.

Delhi Metro's Model Shift Project has been registered as a Clean Development Mechanism (CDM) by the UN and it will earn carbon credits worth about Rs.47 crore annually for the next seven years and with the increase in number of passengers, this figure will increase.

"Today about 18 lakh people travel in the Delhi Metro which is completely non-polluting and environment-friendly. But for the Metro, these people would have travelled by cars, buses, two/three wheelers which would have resulted in GHG emission," the statement said.

GHG gases include carbon dioxide, carbon monoxide, nitrogen oxide, particulate matter and others.

The UN observed that Metro has helped in reducing emission of harmful gases into the city's atmosphere.

"The United Nations Body administering the CDM under the Kyoto Protocol has certified that Delhi Metro has reduced emissions and no other Metro in the world could get the carbon credit for the above because of the very stringent requirement to provide conclusive documentary proof of reduction in emissions," it said.

This is the second CDM project of Delhi Metro to be registered with the UN body in the last three years. Metro's first CDM project was on regenerative braking - a technique for reducing power consumption.

"Every passenger who chooses to use Metro instead of car/bus contributes in reduction in emissions to the extent of approximately 100 gm of carbon-dioxide for every trip of 10 km and therefore, becomes party to the reduction in global warming," it added.