Bathroom exhaust fan maintenance, how to put a filter in

Your fan grate may come with some kind of filter material attached to it. If that material is filthy, just buy a new plastic cover, without filter material in it, for a few dollars at a hardware store. Then you can use this method to put a homemade disposable filter in it. This keeps your fan from getting all dusty and moldy, which is incredibly difficult and gross to clean.