India, Sept. 23 -- Contribution of vehicular emissions to Delhi's PM 2.5 concentrations reduced from 19% during the pre-lockdown period to only 5% during the lockdown period between March 25 and 17. It again increased to 15% during phase 3 of the lockdown in May, a new analysis has shown.

The impact of the nationwide lockdown to halt spread of Covid-19 starting March 25 was visible on Delhi's air quality but a source apportionment study commissioned by Central Pollution Control Board (CPCB) to IIT Kanpur and IIT Delhi has revealed what exactly changed during the various phases of lockdown until May.

The study was referred to by CPCB in its report titled "Impact of Lockdown on Ambient Air Quality" released on Wednesday.

Vehicular emissi...