India, May 27 -- Amid dust intrusion from Rajasthan since Sunday night, Delhi's air quality nosedived and briefly touched the 'very poor' category in the early hours of Tuesday -- the first time since February this year. Though improving marginally during the day, it was still 'poor' in the evening, as Delhi continued to sizzle under high heat.

A haze was visible in the city till Monday night, with PM 10 levels spiking. Delhi's average air quality index (AQI) was 304 (very poor) at 9 am on Tuesday, but by 4 pm, when the Central Pollution Control Board (CPCB) releases its daily air bulletin -- had dipped 254 (poor). It was 252 (poor) at the same time on Monday. The last time Delhi's AQI was 'very poor' -- over 300, was on February 11, whe...