A sharp drop in visibility and haze-obscured skyline marked another low for Delhi on Monday as its AQI touched 498 in the morning and settled at 427 by the evening, with air quality in the hazardous "severe" zone. According to the Central Pollution Control Board (CPCB), 27 monitoring stations across the city recorded "severe" air quality, while 12 stations reported "very poor" levels. Wazirpur recorded the worst air quality among the 40 stations, with an AQI of 475. Notably, CPCB does not register an AQI value beyond 500. As per the CBCP, an AQI between 0 and 50 is considered "good", 51 and 100 "satisfactory, 101 and 200 "moderate", 201 and 300 "poor", 301 to 400 "very poor", and 401 to 500 "severe". Data from the Air Quality Early Warning System for Delhi indicated that PM2.5 concentration stood at 154.96 micrograms per cubic metre, while PM10 levels were recorded at 260.9 micrograms per cubic metre. PM2.5 refers to fine inhalable particles that can penetrate deep into the lungs,