If Delhi’s AQI is just 279, why does it look like 350+?

The Capital on Wednesday was cloaked in gray hazy skies, reminiscent of days at this time of the year when the AQI crosses 350. But it wasn’t.

- Aheli Das

The capital's 24-hour average air quality index stood at 279 in the “poor” category at 4pm on Wednesday, down from 294 on Tuesday and 301 the previous day, according to the Central Pollution Control Board.

Experts say this could be because of meteorological conditions that trap pollutants at low altitudes, and measurement anomalies.

Experts said the apparent contradiction could stem from stagnant atmospheric conditions that prevent pollutant dispersion regardless of emission levels. ‘Temperature inversion — a phenomenon where warm air traps cooler, polluted air near the surface — has intensified as seasonal temperatures drop, creating a visible haze from suspended particulate matter.