Delhi: Improved air quality index worsens by evening; wind speed slows down

The national capital breathed the cleanest air of the year on Wednesday morning with the System of Air Quality and Weather Forecasting And Research (SAFAR) recording the Air Quality Index at 215, which slotted in the ‘poor’ category. The relief, however, was short-lived as the pollution levels spiked to ‘very poor’ by evening. According to the data by the Central Pollution Control Board, the AQI settled at 372.

The AQI had been moderately poor over the last few days due to dry and cold wind from northwest direction that aided in dispersion of pollutants. The wind also decreased humidity level in the atmosphere, hence preventing the pollutants from getting trapped in the moisture surface. However, the wind has decreased in speed and also changed direction. The wind which was earlier blowing from northwesterly, has been changed to easterly and south-easterly due to approaching Western Disturbance. This will also lead to a rise in humidity levels over the area, resulting in shallow to moderate fog. 

Air quality will deteriorate for the next few days. It is, however, expected to improve further over the weekend where rain or thundershowers are expected to lash the city. Rain will wash away the pollutants, making the air cleaner.  

The overall PM2.5 (fine particulate matter in the air with a diameter of less than 2.5 micrometre) level in Delhi was recorded at 180 in the ‘very poor’ category while the PM10 (fine particulate matter in the air with a diameter of fewer than 10 micrometre) level was recorded at 320 under ‘poor’ category, SAFAR said.