Stop the idling vehicle

Yesterday our HK government announced a very creative idea to fight the air pollution problem. Their plan is fines the idling vehicle driver. Certainly impacted many drivers especially those commerical transport vehicle. In my viewpoint, I don't mind to stop the engine when stopped for waiting a couple minutes. I'm not sure how the air quality can be improved by my little contribution, but definitely it can save my dammit expensive petrol. From the air pollution standpoint, does the idle viehicle stopped aside the road is the main cause out of those increasingly car volume. I rather HK government provides more favor to speed up replacing outdated vehicle with low exhaust vehicle. As the car pollution is coming from his exhaust, why not consider the solution such as let more low exhaust vehicle running on the road? So should I change my Pug to Prius to support the environmental?