Despite highest stubble burning, Delhi AQI recovers

 In spite of the highest stubble burning incidents recorded this season, Delhi's Air Quality Index (AQI) recovered significantly on Tuesday to the "very poor" category due to high wind speeds.

The AQI was recorded at 356 with the PM 10 falling to the poor category at 278 and PM 2.5 at 193 in the very poor category.

According to a forecast by Safar India, the AQI is back to very poor as predicted after rapidly recovering from severe largely due to faster winds to flush it out.

The trend seen today also emphasizes the point that stubble burning is just one factor in the overall pollution paradigm.

"In spite of the fact that biomass fire counts observed on Monday were highest of the season (4,962) combined with favourable wind direction north-westerly (coming from biomass fire areas), the Delhi air quality was least affected and continued to recover," the Safar India bulletin said.

"It was mainly due to high transport-level wind speed which rapidly passed over Delhi without descending to only impact the farther region and then getting dissipated having short residence time", it said.

The weather body said this is an illustrative example that how the combination of several factors such as external transport, local emission, and boundary layer dynamics have to act together to have a powerful impact.

High surface and boundary layer wind on Tuesday will improve air quality drastically during the sunny day hours.

"However, slight deterioration to the higher end of very poor to lower end of severe is expected during stable late-night hours and early hours of tomorrow only due to reduced wind speed", it said.

A fresh western disturbance is approaching north India. A change in surface and boundary layer direction is expecting by early November 7. This will reduce stubble fire plume transport. Scattered rainfall is expected to further improve AQI to the lower end of very poor to poor category by November 8, it added.IANS