New Delhi, Jan. 21 -- The Commission for Air Quality Management (CAQM) on Tuesday lifted Stage-4 of the Graded Response Action Plan (Grap) after the air quality improved marginally. The 24-hour average air quality index (AQI) stood at 378 (very poor) at 4 pm - down from a reading of 410 (severe) at 4 pm on Monday, snapping a three day streak where the AQI had been 400 or higher. On Tuesday, Gurugram and Manesar recorded AQI levels of 394 and 328 respectively, both categorised as "very poor". Of Gurugram's four monitoring stations, only three were operational. Gwal Pahari recorded 348, Sector 51 reported 404, and Vikas Sadan registered 418. Forecasts show NCR's AQI is now set to remain 'very poor' in the coming days, even as a western disturbance approaches, bringing possible light rain and gusty winds on January 23. "Delhi's air quality is likely to be in the 'very poor' category from January 21 till January 23. The outlook for the subsequent six days from January 24, shows the AQI will be between 'very poor' and 'poor' ranges," said the Air Quality Early Warning System (EWS) for Delhi. The removal of stage-4 allows the entry of trucks and diesel operated BS-4 Heavy Goods Vehicles (HGVs) in the capital again. It also allows construction and demolition (C&D) activities to resume for linear projects, however private construction and demolition (C&D) activities are still prohibited. The mandatory restriction on schools to conduct hybrid classes between six till 11 (barring 10 and 12) are also lifted. Further, a restriction set by the Delhi government - on non-Delhi registered vehicles below BS-6 - has also been lifted. Stage-4 was invoked in the capital on Saturday, January 17, when the day's AQI began to rise rapidly and crossed 400 in the evening. Typically, stage-4 is invoked when the AQI is expected to cross 450. The CAQM in a statement on Tuesday said it was lifting the measures given the forecast for "very poor" air, "keeping in view the disruptive nature of restrictions, and "considering the trend of improvement in the average AQI of Delhi". Central Pollution Control Board data at 8 am showed that of the 39 active ambient air quality stations in the city, 23 were still in the "severe" category....