While ev 3-wheelers have become quite common in India, I am not sure if they have led to any visible improvement in air quality. The earlier 3-wheelers were already CNG based and not as inefficient as petrol/gasoline powered ones. We are a developing country so I believe the growth in private cars is also offsetting any gains from ev 3-wheelers.

To add to this, the particulates in the air are not entirely from this pollution, it is a sum of our terrain, geography, agricultural activities and pollution.