I have to deal with this every summer, and a couple of ideas.
The AirNow.gov sight is very good at assessing current situation in your area and gives recommendations on who should be exercising outdoors and who should avoid it. See link below.
On the days it suggests as not exercising outdoors for your category of health, hit the dreadmil as others have said. It pays to take care of your pumps. Why risk it?
Masks have been suggested and I got into this area a lot due to my work responsibilities and the only chance you have of protecting your lungs even a little from the ultra-fine smoke particles is a K95 mask that fits you well, and even that is only partially effective. A freakin' paint respirator is actually what you would need to be fully protected, but who would do that?