Air quality in Delhi has deteriorated due to the use of illegal fireworks during the holiday

Air quality in the Indian capital Delhi deteriorated on Monday, November 9, after residents celebrating a Hindu festival of lights set off fireworks despite a court order to ban it.

At 9 a.m. on Monday, Delhi’s air quality index (AQI) stood at 370. India's Central Pollution Control Board has classified this level as "very poor," noting that a reading of up to 50 is considered a "good" indicator.

“According to official data, in many areas of the city with a population of 20 million people, the figure exceeded 400, which is classified as “severe” level of air pollution,” the material says.

Earlier this month, India's Supreme Court ruled that only certified low-pollution fireworks would be allowed for use for a limited time on the Diwali weekend.

Residents in Delhi and Mumbai reported that fireworks continued to explode late into the night.