New Delhi, Nov 7: Air quality in Delhi plunged tonight and visibility levels dropped as moisture combined with pollutants shrouded the city in a thick cover of haze. The Central Pollution Control Board (CPCB) said high moisture level in the air has trapped emissions from local sources and hanging low over the city in the absence of wind. "Total calm conditions, marked by the complete absence of wind has led to the situation. The moisture has trapped emissions from ground-level sources," Dipankar Saha, CPCB's air lab chief, said. Saha said air from neighbouring Punjab and Haryana, where paddy stubble burning is in full swing, is not entering the city as of now. When it starts, the situation is expected to deteriorate further. The CPCB recorded 'very poor' air quality in the national capital. Neighbouring Noida and Ghaziabad, however, recorded 'severe'air quality. The real-time pollution monitors displayed alarmingly high concentration of PM2.5 and PM10, which are ultrafine particulates having the ability to enter the respiratory system and subsequently the bloodstream of humans and animals, causing harm. A 'very poor' AQI comes with the warning that people may develop respiratory illness on prolonged exposure while exposure to 'severe' air affects healthy people and seriously impacts those with existing respiratory or cardiovascular diseases.