A layer of haze lingered over the national capital region on November 5. Delhi’s air quality rapidly worsened to ‘severe’ category. Residents of Delhi woke up to an Air Quality Index (AQI) of 452. An AQI reading of 301 to 400 is associated with respiratory illnesses. IMD said a layer of smoke and pollution settled near the surface on November 4. The layer blocked sunlight and reduced visibility in the national capital region. It said a foggy day is expected with min temperature of 11 degree Celsius. Delhi recorded a minimum temperatures of 11-10 degrees Celsius for past 4 days. The minimum temperature expected to remain around 10- degree mark through the week.