Does the air from the vents pass through the filter?

Under the hood, there is a filter, called an "air cleaner element", to keep dirt, sand, etc., from entering the engine. Does the air that comes out of the vents (heating / air conditioning) into the passenger compartment (a) come from this intake and pass through the same filter, (b) come from another... show more Under the hood, there is a filter, called an "air cleaner element", to keep dirt, sand, etc., from entering the engine. Does the air that comes out of the vents (heating / air conditioning) into the passenger compartment (a) come from this intake and pass through the same filter, (b) come from another intake and pass through a different filter, or (c) come from a different intake and not get filtered?

There are tiny specs of something in the air coming from the vent. Does this mean that I need to replace the filter on the air going to the engine?
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