The national capital's air quality remained "very poor" on Sunday, with stubble burning contributing 40 per cent to Delhi's pollution and negating the effect of better ventilation, according to a government forecasting agency. The Air Quality Early Warning System for Delhi said the air quality is likely to hit "severe" levels tonight, but will slip back into the "very poor" category on Monday. The city recorded a 24-hour average air quality index (AQI) of 364. It was 367 on Saturday, 374 on Friday, 395 on Thursday, 297 on Wednesday, 312 on Tuesday, and 353 on Monday.