I could not find a reference to an air filter in the Parts manual, although there are plenty of oil and fuel filters. Our Technical Manual says this about air filters:
7. Clean Air Filter ifsupplied. (Most models have an air silencer that does not require cleaning.). [p. 20]
I almost never run my blower and don’t notice any exhaust fumes from the engine in the cabin or in the engine compartment. Maybe I need to sniff harder around the engine.