A thick blanket of toxic smog shrouded India ’s capital early on Monday after firecrackers lit up the skies over Delhi during Diwali celebrations, compounding dangerously high pollution levels and intensifying the seasonal air pollution crisis.

Despite restrictions on fireworks, residents in Delhi celebrated the Hindu festival of lights with fireworks on Sunday evening, releasing smoke and fine particulate matter into the atmosphere.

While India’s Central Pollution Control Board showed the air quality index exceeding 400 in several parts of the city, other private monitoring sites showed pollution crossing “hazardous” levels of 2,000 in parts of Delhi on Sunday.

A person wearing a face mask jogs through thick smog after firecrackers lit up the sky overnight during Diwali celebrations in New Delhi, Monday, Nov.…