Actual cabin particulate filters are a recent and fairly engineered item, and usually touted as a "feature" and sometimes as an option. Mostly they're designed to minimize the intrusion of dust and allergens into the passenger cabin, although a few feature odor-fighting construction with activated charcoal or zeolite built into the filter material. You'll usually find these on European and luxury vehicles, almost never on a truck which Isuzu is very much. Our ventilation system is the standard plenum type where outside air enters through the vents ahead of the windshield and then feeds out of the plenum (big air box) into the cabin through the selected vent.

If you ever get some funkadelic odors then likely something has decided to take up damp residence either in the plenum, the plenum's likely plugged drain tubes or even the evaporator. There are a number of products for cleaning and removing such scents, but a good habit to get into is flushing a good amount of mild bleach water through the plenum intake to make sure the drains are clear.