Noida, Dec. 14 -- Air quality in the National Capital Region plummeted sharply on Saturday, with at least four cities recording a "severe" air quality index (AQI) and accounting for four of the five cities across the country that recorded AQI readings above 400. Among these, Noida fared the worst, recording an AQI of 455 (severe+), and was the only city to breach the 450 mark. Gurugram, on the other hand, fared relatively better, clocking an AQI of 322 ("very poor") on the day. According to the Central Pollution Control Board's (CPCB's) daily AQI bulletin, Delhi recorded an AQI of 431, Greater Noida recorded an AQI of 442, and Ghaziabad recorded an AQI of 430, all of which are categorised as "severe". On Friday, Ghaziabad recorded an AQI of 363, Noida 386 and Greater Noida, 373 -- all "very poor". Experts attributed the spike in pollution to slow wind speeds and unfavourable meteorological conditions that hindered the dispersal of pollutants. "Over the past few days, moderate winds had helped temporarily improve air quality across Delhi NCR. However, an approaching western disturbance over the western Himalayas led to a reduction in wind speeds over the northern plains," said Mahesh Palawat, vice president of climate and meteorology at Skymet Weather. He said that between Friday and Saturday, winds remained light during the daytime and nearly calm during the night, allowing pollutants to accumulate near the surface, and pushing the AQI into a hazardous range. The Commission for Air Quality Management (CAQM) in NCR, in a meeting on Saturday, held to review the status of sector-specific enforcement by NCR governments, surprisingly noted that the NCR districts of Uttar Pradesh (UP) fared relatively better. "NCR Districts of Uttar Pradesh exhibited comparatively satisfactory performance towards abatement of air pollution in the region. However, it must establish and comply with the timelines committed for focused action(s), especially for the vehicular sector," the CAQM said. A deadline of December 31 has been given for the development of the web portal for vehicle aggregators, delivery service providers and e-commerce entities for NCR districts of Uttar Pradesh and Rajasthan....