This Diwali, the Delhi's air quality is likely to be relatively better than last year, when level of pollutants had reached perilous proportion, SAFAR, a union government agency, has forecast. The SAFAR forecast is based on the study of prevailing meteorological conditions, which include low upper wind movement, a situation which prevents pollutant-laden air from stubble-burning regions from entering Delhi. According to the forecast, air quality index (AQI) will remain 'very poor' if bursting of firecrackers is down even by 50 per cent compared to last year, but it will turn 'severe' if the same volume of crackers are set off.\u00a0 However, since moisture in Delhi's air is increasing and morning temperature dipping, it may lead to an increase in the atmospheric holding capacity of the emissions coming from firecrackers, SAFAR said. "There is no likelihood of repeat of 2016. Upper air winds which transport pollutants from distant sources such as the Indo-Gangetic Plains or the stubble-burning regions, are quite low and unlikely to impact Delhi significantly," it said.\u00a0 The anticyclone conditions are looming large, which is linked to withdrawal of monsoon and it may lead to slowing down surface winds resulting in slowing dispersion and stagnation of local pollution, it said.\u00a0 According to the forecast, the highest levels of PM10 and PM2.5, which are ultrafine particulates, are expected between 11 pm to 3 am on the intervening night of October 19- 20 and air quality will start improving further from Oct 21. SAFAR, which operates eight monitoring stations in Delhi, said the share of PM2.5 (relatively more harmful than coarser particles) in PM10 is expected to remain unchanged unlike last year when it had increased by 10-20 per cent during the Diwali period, which had made the air more toxic.\u00a0 A "very poor" AQI essentially means that people may suffer from respiratory illness on prolonged exposure to such air. On further dip in air quality, the AQI will turn "severe", which may trouble even healthy people and seriously affect those with existing diseases.