This is an extremely important question. I am glad that you already know about the health benefits. Let me give you a few more benefits of reducing smog.
First, closely related to health benefits, there will be a lot of savings on medical costs. When when consider that air pollution (smog) affect not just a small percentage of society, we are now talking about billions of dollars in saved heath costs.
Second, with the reducing of smog, there will be a greater harvest in terms of food.
Finally, in order to get rid of smog, there needs to be a greater green push. When this happens, more jobs are created. This will, in turn, pick up the economy.