The national capital is in a dual fight against the novel coronavirus and air pollution. Delhi recorded its air quality in the "very poor" category on Thursday with experts and government agencies saying it may enter the "severe" category on Diwali night. A change in the wind direction – from north westerly to north-north easterly – was the reason behind the dip in pollution levels as it reduced the contribution of stubble burning significantly, they said. Meanwhile, the national capital reported its biggest single-day spike of 8,593 coronavirus cases on Wednesday that took its infection tally to over 4.59 lakh people, while 85 new fatalities pushed the national capital's death toll to 7,228.