Orange alert on weather; curbs back as AQI'severe'

Delhi on Sunday was smothered in a thick smog that severely dented visibility and led to over 400 flights being delayed, as pollution levels soared into the dreaded "severe" zone for the first time this year and the minimum temperature fell to its lowest this season With schools set to reopen after the winter break on Monday despite the chill, the state government ordered institutions to begin all in-person classes only after 9 am.

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Little is likely to change on Monday and Tuesday at least, the weather office predicted, warning of yet another spell of impenetrable fog in the morning and more icy temperatures as it issued an orange alert for both days. An orange alert warns people to be prepared for inclement weather and consequent disruptions to everyday life.

The city's 24-hour average air quality index (AQI) worsened to 447, according to the Central Pollution Control Board's (CPCB) official 4pm reading, giving Delhi its worst January air in three years.

This AQI was also significantly worse than 399 (very poor) on Saturday, a deterioration that pushed the Commission for Air Quality Management (CAQM) to once again clamp down on the use of older vehicles as well as on private constructions across NCR.

Such noxious air leaves even healthy people susceptible to serious long-term illnesses, while the outlook is even more bleak for children, the elderly and people with existing illnesses.

Meanwhile, the minimum temperature dipped to 3.5°C, four degrees below normal, keeping the city in the grip of a "cold wave" for a third straight day.

The India Meteorological Department (IMD) declares a "cold wave" when the minimum temperature is 4.5°C or more below normal. The agency can also declare a cold wave in the plains when the minimum reading is below 4°C, as has been the case in Delhi for three days. The temperature was 3.6°C on Saturday and 3.9°C the day before that.

The maximum temperature, however, was 20.6°C, a degree above normal and the highest this year.