Have you at any point asked why the air inside your home is not the same as outside? Did you see the thing that matters is just clear when you turn your AC or Furnace on? At that point, old buddy, you're needing an air vent cleaning. Following quite a while of ignoring cleaning your vents, form, residue, and trash gather inside your vents, preventing the effectiveness.
Air Duct Cleaning
Air Vent Cleaning
AC Cleaning