India, Nov. 10 -- More stubble fires than previous years and unsuitable weather conditions have negated the gains made in terms of more good and satisfactory air days as well as the annual average PM2.5 and PM10 concentrations on account of a prolonged lockdown to curb the spread of Covid-19, experts said.

They said consecutive days of severe air quality days or an air emergency episode like the present one wasn't recorded since 2016. The present smog episode will be the worst since AQI is being measured if severe air quality persists till Wednesday. Experts said the improvement in air quality over Delhi being recorded in the past two years will be negated because of severe air pollution this winter.

In 2018 and 2019, 159 and 182 good t...