A thick haze of pollution has descended on Delhi, leaving experts worried that the conditions over the Diwali weekend are likely to be the worst in the past three years. The Centre’s System of Air Quality and Weather Forecasting and Research declared that the the air quality was “severe” on Saturday and will be even worse on Sunday and Monday, The Hindu reported. Experts suggest that when a severe alert is put, people should avoid strenuous physical activity outdoors, especially children, the elderly and those with lung or heart problems.

The Air Quality Index fell well below acceptable levels, hitting 443 on Sunday, and is expected to touch 472 on Monday. Any reading above 300 is considered “very poor”, while it is rated “severe” beyond 400. At severe levels, even healthy citizens are considered at risk for breathing difficulties. The conditions will improve only after November 1, the agency said. The levels of particulate matter in the air, which determine pollution, became higher than those in 2014 and 2015 after October 25, officials told The Hindu.

The government claims agricultural fires from the neighbouring states of Punjab and Haryana are “a major contributor” to the pollution in the Capital, along with “inversion and calm meteorological conditions". The meteorological department said low wind speeds had caused pollutants to remain suspended in the air.