smog air pump filter?

I'm curious if anyone knows if there is a filter in the air pump (the one connected to the Air Switching Valve for smog)

Reason being is that in older trucks I own there is a filter; it seems reasonable to me that you'd want one to keep unwanted contaminants away from things like O2 sensors and catalytic converters (albeit that danger seems minimal).

Although the FSM shows the procedure of removing and installing the air pump, it doesn't show the breakdown of how it's assembled.

When you take off the small cap on the side of the air pump, there is no filter - so I'd thought I'd ask you guys because my local dealership didn't even know what an air pump was.

This is in reference to a 2TR-FE engine

Thanks