Commuters board buses in New Delhi on Jan. 15., 2016. Air quality levels remained "very unhealthy" that day, the final day of the two-week experiment in allowing private cars on the roads only on alternate days. (Prakash Singh/Agence France-Presse/Getty Images)

Regarding the Jan. 12 news article “Court allows Delhi’s effort to clear air”:

Although Delhi’s air pollution is jaw-droppingly bad, city administrators should think long and hard about extending the trial of their odd-even policy, which prohibits cars from being driven every other day based on the last digit of their license plate.

In Bogotá, Colombia; São Paulo, Brazil; Mexico City and other developing megacities with similar programs, drivers have quickly adapted in ways that have negated intended air pollution benefits, including by purchasing second vehicles (often old, highly polluting clunkers) and shifting trips to unrestricted days and times. Moreover, the costs to drivers are enormous. A recent study shows that in Mexico City in 2013, costs exceeded $350 million, which is roughly 3 percent of the city’s gross domestic product. Investments in public transportation, fuel taxes and congestion fees are likely to be more cost effective.

Allen Blackman, Washington

The writer is senior fellow at Resources for the Future, a nonprofit, nonpartisan environmental economics research institute.