Clean headlight lens?

Does anyone know if you can get rid of the foggy coating that forms on Lumina headlight lenses? It looks like oxidized plastic. I'm not sure if it's on the outside or inside. I tried car polish but it only got rid of some, and it seems to have later come back worse.

try using plastic polish, it's specifically formulated to remove yellowing and scratches from plastic lenses and windows(like in convertibles and Jeeps)

Get turtle wax polishing compound. Works great for headlights. :iceslolan