Farmers 100 miles north in Punjab were well aware that they were contaminating the capital’s air, they said in interviews, and were willing to consider other ways to dispose of the excess straw, but could not afford the options offered by the government.

“We are smart, and we have adopted new technology in the past,” said Jaswant Singh, 53, as he watched a fire sweep across a 20-acre field near his village, Maulviwala, about 140 miles northwest of New Delhi.

He planned to set his own seven-and-a-half-acre rice paddy ablaze in a couple of days, he said, “because we can’t afford to pay for the new technology ourselves.”

The air was thick with smoke that evening as I drove the two hours back to Punjab’s capital, Chandigarh, after spending several hours with Mr. Singh and other farmers. The smoke made it hard to see, slowing traffic to a crawl, and breathing was difficult. My lungs hurt with each breath, even though I have never had respiratory problems.

The smoke rising from the fires visible on farms on either side of the road would most likely reach Delhi in another week, depending on the wind’s strength and direction. Farmers began burning their fields two weeks ago, and levels of the smallest particles, called PM 2.5 and believed to pose the greatest health risk, were already soaring.