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Insights into Editorial: Trying and testing the car formula

Insights into Editorial: Trying and testing the car formula

12 January 2016

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It’s been two weeks since the Delhi government implemented the Odd-even formula in the National Capital Region on a trial basis. Yet, there has not been any credible data to support the Delhi government’s claim that the odd-even trial has reduced pollution or improved air quality.

  • Contrary to the claim, the quality of air in the first week of January was worse compared to previous weeks.

What the data suggest?

Data obtained from the National Air Quality Index (NAQI) portal shows that air has been toxic all through this winter. From the available AQI values across eight pollution-monitoring stations in Delhi, the following observations were made-

  • It was found that November had 7 days in the ‘severe’ category, 19 in the ‘very poor’ category, and 4 in the ‘poor’ category.
  • December saw 20 days fall under the ‘very poor’ category and 11 days under the ‘poor’ category.
  • However, in the first week of January, all seven days fell under the ‘very poor’ category. Even the peak value of PM2.5, which the government claims has been lowest during the odd-even trial compared to earlier peaks this winter, is either comparable or just slightly lower to peaks observed from the beginning of December.
  • On average, AQI values for Delhi for the first week of January were 20 to 25% worse than during the preceding week.
  • Various other studies, too, showed that the quality of air in the Capital continuously deteriorated from December 25, with pollution levels being “severe” on four out of the first eight days of January, worse than the previous week.

What can we conclude from the findings mentioned above?

It should be clear that the scheme did not worsen air quality; meteorological conditions did (Wind, which disperses pollutants, has fallen consistently in speed since December). But the scheme was not able to mitigate this impact.

  • Thus, it is disingenuous for the government to claim either that the odd-even trail has improved air quality or that, but for its scheme, the air quality would have been worse given the weather conditions, since it has simply no way of establishing this without better modelling.

What else the data suggest?

What is clear from data about sources of air pollution in Delhi is that cars are not the major polluters.

  • A report by the Indian Institute of Technology, Kanpur, on the sources of particulate matter finds that vehicles contribute to 20% of PM2.5 concentration.
  • Among them, trucks and two-wheelers together contribute to 80% of pollution; cars, 10%. This means that the contribution of four-wheelers to air pollution in Delhi is just 2%.
  • On a given day, when half the cars are taken off the road during the odd-even trail, with additional exemptions, only a 0.5-1% reduction in pollution can be expected. This could be marginally higher depending on the impact of the wind.
  • Thus, it can be concluded that cars are not the main cause of Delhi’s pollution.

How the air quality can be improved?

The government, in the spirit of experimentation in which it initially announced the scheme along with a series of other measures, must continue to try to see what improves Delhi’s air quality. The odd-even scheme expected to show a positive impact in the coming weeks. Other measures-

  • An odd-even trial in the summer months might be more useful to isolate its impact.
  • The government’s proposal to vacuum-clean roads in April is promising, given that the IIT Kanpur study attributed 38% of pollution to road dust.
  • The government could also resort on other measures including temporary controls on industry and construction, and banning the use of fireworks.
  • In the long run, an essential step would be to draft a new transportation policy, without emphasising only economic aspects as was done earlier. Consulting urban planners, logisticians, sociologists, environmentalists, civil society groups including doctors, teachers and lawyers, the police and the military, apart from economists would be essential.
  • CSIR’s proposal- mid-week work-from-home– can be a game changer too. According to this formula, instead of commuting to work and school, employees and students could work and study from home for a day.


Consensus has it that the solutions like the odd-even ones are short-term. However, it is wrong to say that the experiment should not have been conducted. India’s federalism allows for a vast array of public policy experiments, and the Delhi experiment is one of the few related to environmental pollution in India. The Aam Aadmi Party’s ability to take bold steps, convince people to take ownership of these steps, and force both a conversation and behavioural change is truly remarkable. But an experiment must be built around an open-ended question, which has not been the case so far. The greatest success of the scheme has undoubtedly been the fact that emergency levels of pollution are now being hotly discussed by citizens. The AAP government has before it a unique opportunity, which it should not squander away by asking the wrong questions or refusing to hear the answers to its questions.