NEW DELHI: After breathing relatively clean air over the past two days, Delhi once again slipped back into the ‘very poor’ category on Monday with the air quality index (AQI) rising to 326 . AQI was recorded at 298 on Saturday and 292 on Sunday, both falling in the ‘poor’ category.Experts said local emissions from cars rose along with a sharp drop in the minimum temperature, resulting in the spike in the air pollution level. The minimum temperature was recorded at 9.4 degrees Celsius, three notches below normal. It is going to be around 10 degrees Celsius on Tuesday.Although northwesterly winds are blowing once again, stubble burning is now not affecting the region, said experts. “It is a purely localised effect now. Local factors will decide how the air quality improves or deteriorates,” said Dipankar Saha, head of CPCB’s air laboratory.“The pollution levels are expected to rise in the next few days but the difference won’t be too much,” said Gufran Beig , project director at SAFAR. Delhi saw cleaner air over the weekend due to the rain in and around Delhi that settled particulate matters, he added. “Levels have risen slightly due to localised weather conditions as temperatures are dropping and the moisture content has risen slightly.”Monday’s AQI can result in “respiratory illnesses due to prolonged exposure”, according to CPCB. Delhi recorded its cleanest air in over a month on Sunday when AQI fell to 292 for the first time since pre-Diwali days.System of Air Quality and Weather Forecasting And Research (SAFAR) of the ministry of earth sciences recorded Delhi’s average PM2.5 levels at 154 micrograms per cubic metre, while the PM10 levels were at 243. Forecasts show a gradual rise in these levels too over the next three days due to localised weather conditions.Delhi’s average PM2.5 concentration remained around two-three times the safe standard with DTU being the most polluted location at 372. Ghaziabad was the most polluted location in NCR with an AQI of 368 while Faridabad was the cleanest with an AQI of 291.