If the trip costed 10 minutes moving, yes the comparison would be between a car moving for 10 minutes and one that idles for some time and then moves for 10 minutes. But congestion makes the cars move slower, and at congestion speeds the amount of pollution increases very quickly with reduced speeds.
If the trip costed 10 minutes moving, yes the comparison would be between a car moving for 10 minutes and one that idles for some time and then moves for 10 minutes. But congestion makes the cars move slower, and at congestion speeds the amount of pollution increases very quickly with reduced speeds.