Air pollution does kill more people than smoking does. In fact, if you want to get a technical answer, it kills twice as many people as smoking does. It comes by way of smog that may burn your throat and makes your eyes hurt but it is actually doing damage to your entire body. Just one deep breath in a polluted environment might send a bunch of very fine particles into your lungs. Then, it enters the rest of the body such as in your blood stream. It then goes all over - to your heart and everywhere else.
Children, babies, the elderly, and even those who eat healthy are all subject to air pollution and it is killing us all. Those who preach against cigarette smoking often thing nothing about driving a car that emits a lot of exhaust fumes. Air pollution and heath is a subject that isn't addressed near enough but certainly should be.