India's capital city has acquired a reputation for being the most polluted city in the world. The World Health Organisation has declared that Delhi has the highest concentration of particulate matter of less than 2.5 microns - PM2.5 - globally, at 153 microgrammes. Beijing, famed for its dirty air, has a PM2.5 of 56 microgrammes. The effect on citizens' lungs is immense. Air pollution is already the fifth largest killer of Indians, according to the Centre for Science and the Environment. Clearly, Delhi faces a public health emergency, and it is good that the Delhi government has chosen to respond. The government has taken several decisions last week to deal with the problem. The thermal power plants at Badarpur and Rajghat are to be shut down, and the National Green Tribunal will be petitioned to shut down the plant at Dadri, in western Uttar Pradesh, as well. From 2017, Euro-VI emissions norms for cars will be implemented. Streets will be cleaned using vacuums to suck up dust - construction activity and climatic conditions, as well as the cutting down of trees, have added to the amount of dust in the air.
But perhaps the most attention has been fixed on the immediate step the government intends to take: which is to temporarily introduce a system of road rationing, by which cars with even and odd numbers on their licence plates run on alternate days of the week. It is not yet known for how long these restrictions will be enforced and the details are yet to be worked out. Will it apply to all cars in Delhi, even those that come in from the rest of the National Capital Region? Will state and central government cars be exempt? What about taxi fleets? Yet it has understandably led to considerable concern and protests on social media. Single-car households will struggle to adapt, given the short notice. There are legitimate questions as to whether such a measure would be another source of harassment of ordinary citizens, given the limitations of both the city's existing public transport infrastructure and the efficiency of the law enforcement agencies.
Odd-even road rationing, as it is called, has been tried elsewhere. In general, results suggest that it reduces pollution between 18 and 20 per cent in the short term in most places that it has been tried; if it becomes permanent, however, then adaptation takes place and the restriction becomes ineffective. Clearly it can only be used as a short-term emergency measure - and, certainly, Delhi's air in the coldest weeks of winter, when the earth is not sufficiently hot enough to ensure circulation of dirty air, constitute a clear and present danger. However, any such measure will be hugely disruptive. The Delhi government has been in power for several months, and it could have planned more sensibly for such a measure to come into place, and prepared people for it. There are legitimate questions also about how it will be implemented. In most other jurisdictions where road rationing has been tried, the police have been the primary instruments of its implementation. The Delhi government does not control the local police, however, and their relationship has been adversarial. Previous attempts to control traffic - such as the Bus Rapid Transit corridor of the previous government - foundered on police non-cooperation. The worst-case scenario will be that this measure will be tried out suddenly and without preparation, cause chaos, and be reversed without any further ado - leaving Delhi's air still unchanged. Delhi needs measures to improve its air quality, but with an integrated approach that should also include a clear plan for strengthening the public transport infrastructure.
