Thanks for all the imput.

Actually I wasn't asking for medical opinions. LOL.

The main point of the question was-- should the ducts be cleaned or is
it something that is unneccesary because the filter works fine.

The house is about 15 years old, but I have noticed some dust around
the vents. However, I changed the filter and it is an industrial
strength $40 one-- the size of an accordian. I guess it is always
useful to tune up the furnace and AC. At this point, it sounds like I
should pass on the vents for a while.