A Delhi Metro official said that at present, about 18 lakh people are travelling by metro, which is non-polluting and environmental friendly. These people have been travelling in trains only because of metro or else they would have used other means to commute resulting in the emission of green house gases.
United Nations-body administering the Clean Development Mechanism (CDM) under the Kyoto Protocol has certified that DMRC has reduced emissions.
According to the DMRC, "no other metro in the world could get the carbon credit because of stringent requirement of the United Nations-body to provide conclusive documentary proof of reduction in emissions. It is difficult to give documentary proof of the difference of energy consumption of two scenarios with metro and without metro."
The Delhi metro has helped in the reduction of around 91,000 vehicles from the city roads, where the number of vehicles were much higher than in other cities like Mumbai, Chennai and Delhi in the past two decades.