In the first weeks of November 2023,¬† to tackle issues of poor air quality, the Delhi Government proposed implementing an odd-even vehicle rationing scheme, pending Supreme Court approval. To support the odd-even scheme’s efficacy, the government cited a study on the program’s impact involving EPIC researchers in an affidavit sent to the Supreme Court. The study was done in collaboration with researchers from ¬†Evidence for Policy Design (EPOD), who rigorously evaluated the two rounds of the odd-even scheme implemented in the capital in 2016.

Background

In January and April 2016, the government of Delhi piloted an “odd-even” traffic rule which mandated that only cars with odd (even) numbered license plates could ply on odd (even) dates. Later that year, researchers from EPIC used high-frequency measures from air quality monitoring stations to estimate the program’s impact.

The Research

The study by EPIC researchers used high-frequency data from monitoring stations to compare fine particulate concentrations in Delhi (where the odd-even policy was implemented) to those reported for the neighboring towns of Faridabad and Gurgaon (where the policy was not implemented). The analysis period spanned the six months between November 2015 and April 2016.

The Results

The study found that in the January round of odd-even, pollution fell by about 14% during the day relative to NCR regions where odd-even was not in force. However, because the vast majority of pollution is currently owed to crop burning, not vehicles, there is no reason to expect a similar percentage decrease from odd to even in November. Policies like congestion pricing that reduce vehicle use will be helpful outside the crop-burning period.
Relative to surrounding satellite cities, fine particle concentrations in Delhi’s air were lower by 14-16% during the January pilot. In contrast, the program did not affect Delhi’s air quality during the warmer month of April. This suggests that the main value of an “odd-even” program is as an emergency measure during winter months when car emissions play a more prominent role in affecting air quality.

The Impact

The credible evaluation done by our researchers caught the government’s attention. It was subsequently included in an affidavit in November 2023 that the Government of Delhi sent to the Supreme Court, citing the program’s efficacy as an emergency measure. Using this research in making a case by the government is one of the many examples that shows the importance of evidence-backed analysis that helps authorities suggest and implement better strategic solutions and policies. The collaborative efforts between research and governance are not only empowering but are also shaping a future where policies are not just ideated but meticulously informed, ensuring a more resilient and adaptive approach to the intricate challenges of the modern world.