Calm winds at night mean AQI poorest when kids go to school

The Capital’s air quality is at its worst every morning after a night of still winds, leaving children heading to school particularly vulnerable to a host of health hazards posed by noxious pollution levels, shows data, underscoring yet another impact of Delhi’s annual smog emergency.

- Jasjeev Gandhiok

Data from the Central Pollution Control Board showed that Delhi’s real-time hourly average air quality index (AQI) largely remains “severe” all morning, before improving marginally around noon, when the temperature rises and winds pick up.

Delhi’s schools reopened on Monday after the state government imposed an early winter break, prompted by the city’s consistently ‘severe’ air quality index (AQI).

On November 6, the Delhi government ordered schools to shut till November 10 for primary classes, as the city’s air quality nosedived. On November 9, as a shroud of smog cloaked the city, the government rescheduled the winter break, ordering schools to remain shut between November 10 and 18 for all classes.

Still, with schools now open, children are exposed to the worst of the city’s air.

For instance, Delhi’s hourly average AQI was 413 (severe) at 9am on Wednesday. It worsened to 422 by 11am, before winds began picking up across the city. The AQI at noon was 420, but by 2pm, improved to 330 (very poor). It remained in this zone till around 6pm. However, as night crept in, pollution levels worsened again. At 9.30pm, the hourly AQI shot up to 390, according to CPCB’s Sameer app.

To be sure, hourly averages are not collected for the agency’s official 4pm bulletin, which instead takes into account the 24-hour AQI value.

Climate experts said that even with winds picking up during the day, low temperatures and calm winds at night allow pollutants to accumulate.