Trucks cant enter Delhi for 3 days after Diwali as it was the ban on trucks by the Environment Pollution (Control and Prevention) Authority. From 8 to 10th of November trucks were banned to control pollution in Delhi.
Due to Diwali pollution level was increased in high level and the quality of air degraded. So in order to curtail more pollution trucks were banned post-Diwali in Delhi. The central pollution control board held a meeting to review the ambient air quality of NCR and also recommended this banning of trucks carrying lots of polluted air.

EPCA chairperson bares all wrote to all four NCR states that “You are requested to direct all authorities, particularly the police, to coordinate action on this, so that trucks are turned around before entering Delhi. You are also requested to put out information on this at the earliest so that transporters have noticed and can plan their travel accordingly."
There was also a request made to people for not using private cars in this period as they can create more pollution. It was just an initiative taken to curtail pollution and give us a healthy environment to survive more.