India, Dec. 28 -- New Delhi/Gurugram/Noida/Ghaziabad

Air quality in the National Capital Region plummeted once again on Saturday, with Noida and Ghaziabad recording "severe" air quality index (AQI), while Delhi and Noida were on the brink of breaching the "severe" category, according to the Central Pollution Control Board's (CPCB's) daily national bulletin and real-time data.

The India Meteorological Department (IMD) has issued a yellow alert for Sunday morning, warning of moderate to dense fog and cold wave-like conditions, which will keep wind speed slow and AQI at the same level, experts said.

According to the CPCB's 24-hour average bulletin, Noida recorded an AQI of 409 ("severe"), and neighbouring Ghaziabad clocked an AQI of 404 (...