Delhi is Data Deficit

Full article @ Indian Express - Anyone who attempts to estimate vehicular pollution in Delhi has to rely on assumptions. This is because no one has ever taken a random sampling of various vehicles and measured their emissions while they are on road. So no one knows what CNG buses, taxis or three-wheelers of different ages actually emit while operating at different speeds. All of us are forced to estimate these numbers from new vehicle test results or data from abroad. 

More on Delhi's Air

For example, every chemist knows that NOx is not produced by the fuel used but by Nitrogen and Oxygen in air combining when any fuel burns in an engine. The amount produced increases with increase in temperature of combustion. Diesel engines produce more NOx than petrol engines because diesel burns at a higher temperature than petrol. But, CNG also burns at a much higher temperature than petrol and therefore it is possible that all CNG vehicles produce more NOx, creating more Ozone than petrol cars. But there is no discussion on this issue. No one knows how many cars and motorcycles operate in Delhi; official statistics appear to be much higher than actual figures.

Almost 15 years ago, R. A. Mashelkar, as chair of the expert committee on auto fuel policy, had attempted to estimate the number of vehicles in Delhi. His study informed us that actual number of operating vehicles was about 60 to 65 per cent of the registered numbers; the transport department ignored the findings. The numbers made sense to me because over the past 25 years, I have sent four vehicles to the junkyard but still possess all the registration certificates. It appears that most people never have a vehicle deregistered. Two years ago, we did surveys in Delhi, Rajkot and Vishakhapatnam to understand whether the Mashelkar Committee report was still usable. Our results confirmed that the number of cars and motorcycles actually on the roads of Delhi might be only about 50 to 55 per cent of those registered.

news and data links from Delhi's odd/even days

The best decision taken yet is the move to introduce Bharat VI emission and fuel norms as soon as possible. This will be a major improvement over the present situation. In the meantime, we must start working more seriously on detailed cost-effective studies to ensure various options are available to draw up time-bound programmes with measurable milestones. At this juncture, it is very important to remember M.K. Gandhi’s time-honoured advice: “Action in the absence of knowledge can be dangerous and worse than no action at all”.