Do motorcyclists inhale much more air pollution in tunnels than car drivers?
On the one hand, motorcycle riders don't have a button for internal air circulation, but on the other hand a motorcyclists won't be hindered (as much) by traffic jams. So, in case there is no traffic jam and the motorcyclist would take as much time passing though the tunnel as a car driver, the answer would probably be yes. In case of a traffic jam and in a car without internal ventilation, the car driver will presumably be exposed more. When comparing with a car driver in a traffic jam in a car with internal ventilation, it will probably depend on the time spent in the traffic jam.