It’s hard to think of a more contentious public policy in recent years than the Aam Aadmi Party’s (AAP) odd-even scheme. Those who support it love Delhi’s congestion free roads and reduced air pollution. Those who oppose it say that the reduction in air pollution is minimal, and less traffic isn’t really what the scheme is about. The supporters reply that less traffic equals lower emissions as transit times are reduced. To which the naysayers respond that while vehicles may be wasting less fuel stuck in jams, they have to make more trips to compensate for the rationing, which translates to more emissions per vehicle.

The scheme has become a tool for scoring political points. As parties bickered about the scheme, its effectiveness remains dubious. Even research organisations charged with scientifically analysing its efficacy haven’t been able to reach a consensus.

Sunita Narain, director general of the Center for Science and Environment (CSE), came out in support of odd-even, based on CSE analysis. “We have analysed two weeks of January and we have said clearly that while the pollution level didn’t come down, the pollution peak did come down,” she said.

Conversely, Sumit Sharma, Fellow, Centre for Environmental Studies at The Energy and Resources Institute (TERI), said that while there was reduction in congestion due to the scheme, on the air pollution front, “there was some reduction, but not huge”. Sharma explained, “The reason is that the overall share of private cars in the pollution levels of Delhi is very limited. So you cannot expect the scheme to have a huge impact on pollution levels.”

According to Sharma, the challenge for scientific analyses is to “delineate the impact of emission reduction from odd-even scheme from the atmosphere”.

Failure to overcome this challenge has led to uncertainty regarding the analysis which, along with the inconvenience the scheme causes to the public has created much resentment against it. In the heat of the debate, though, it is usually forgotten that the odd-even scheme is not a panacea for Delhi’s pollution woes.

Narain, while supportive of the scheme, said, “It’s an emergency action which should be used when pollution levels are high, like in winter, and we need to bring down the peak [pollution].”

It would perhaps be more helpful to identify other sources of Delhi’s pollution and the long-term measures which might help us tackle them. The findings of an IIT-Kanpur study released in January 2016, based on data taken between November 2013 and June 2014, sheds light on this issue. According to the study, the biggest contributor to both PM 10 (particles with diameter of 10 microns or less) and PM 2.5 emissions (particles with diameter of 2.5 microns or less) is road dust. Road dust is responsible for 56% of PM 10 emissions and 38% of PM 2.5 emissions. Vehicles are the second biggest contributor to PM 2.5 emissions at 20%, but the emissions from domestic fuel burning (12%) and industrial point sources (11%) are also not insignificant. Vehicles come in at a distant fourth (9%) for the top sources of PM 10 emissions, with road dust (56%), industrial point sources (10%) and concrete batching (10%) all exceeding it.

The study also points out that the effect of vehicular pollution on PM 2.5 emissions is higher during winter, averaging 25% and can even reach 35% at certain locations. Moreover, the contribution of diesel vehicles to total vehicular pollution is substantial.

In addition to these sources, the study identifies diesel generator sets, burning of garbage and coal-based tandoors used in hotels and restaurants as major sources of air pollution. It highlights the importance of the entire National Capital Region to take measures to reduce air pollution as one-third of Delhi’s PM levels can be attributed to emissions from outside Delhi.

The study also suggested a number of recommendations that would go much further in reducing air pollution than the odd-even scheme.

• Major roads in Delhi, if swept twice a month can lower road dust emissions by 23%. If the roads are swept four times a month, emissions can be lowered by 52%.
• As far as vehicular pollution is concerned, the study recommends diesel particulate filters, promotion of electric vehicles and bringing down sulphur content in fuels as effective means of controlling emissions. If implemented, these recommendations can lead to a 51% drop in vehicular emissions.

According to Sharma, “the efficiency of air pollution control equipment installed at [industrial] stacks is very important”. Equally important is the quality of coal used by power plants. As for diesel generator sets, uninterrupted power supply would make them unnecessary.

Whatever good it may or may not do to the environment, the odd-even scheme has ended up being bad for the course of public discussion about air pollution. Political one-upmanship and public outrage have turned it into a distracting side-show which hinders us from asking bigger questions and taking long-term measures. As Sharma puts it, “you need a comprehensive air quality management plan. You cannot take measures here and there and expect [to reach] prescribed air quality levels.”