ROHTAK, India — Diwali is the Hindu festival of light, and during the height of the celebrations in India each autumn, much of that illumination is coming from barely controlled explosions: the firecrackers, sparklers and other fireworks that millions here love to ignite as night falls.

But beyond the light, it all adds fumes and smoke to India’s already toxic air. So changes are coming.

Facing expanding evidence that India’s air pollution has become a public health disaster, the government has dramatically rewritten rules on fireworks sales, stringently enforcing a Supreme Court ban on most pyrotechnics and allowing only a handful of “green crackers” to be sold nationwide.

The restrictions have become even tougher ahead of Diwali festivities this weekend, as the celebration coincides with the seasonal onslaught of the country’s worst pollution. To prepare, the authorities have raided illegal fireworks factories and arrested people accused of selling polluting crackers on the black market.