Widespread rain brought Delhi's AQI below 100 on Friday morning, offering relief after days of pollution. Here's how long the capital's air is expected to remain clean as October draws to a close. Delhi's air improved by a whopping 78.5% in just 24 hours, with the city's Air Quality Index (AQI) falling from 363 on Thursday morning to 78 on Friday morning, October 30, according to AQI.in data recorded at 9:31 am.