The danger is in the pyrolized oil. Every entity knows there is a serious health problem with exposure, yet none will take responsibility. These fumes are the equivalent chemically to chemical weapons. The neurological damages are numerous. Air crew are not covered by OSHA oversight. As far as I know, Spirit is the only American airline that has a very specific checklist for fumes. Many times fume events happen after an engine wash because corners are cut. Ask me how I know.