No one anticipated that an initiative to save groundwater by delaying the annual rice season would aggravate northern India’s already miserable air pollution.

Hundreds of millions of Indians breathe some of the world’s most toxic air all year round. Air pollution in the capital area that’s home to about 30 million people is especially stubborn. In winter, the cold weather actually makes the smog even worse — and potent.

Several major Indian cities, including New Delhi, are engulfed in a dense blanket of smog, significantly compromising the air quality and posing substantial health risks to residents. Reports suggest that in some areas,