For more than twenty years, concerns have been expressed in reports from Australia and overseas about a possible relationship between exposure to fumes from heated engine and hydraulic oils contaminating air drawn into aircraft air conditioning systems in certain types of aircraft, and post-exposure acute and chronic symptoms experienced by some cabin occupants. Most reports involve aircrew - both pilots and flight attendants. The term Aerotoxic Syndrome' has been used by some to describe the symptoms experienced, although this term is not accepted as a recognised medical diagnosis. Although a number of inquiries have been undertaken, both in Australia and internationally, the results have been indeterminate, due in part to the difficulty in finding satisfactory evidence. In 2007, in response to persisting reports from Australia and overseas about possible links between the contamination of air supplied to the aircraft cabin and descriptions of post-exposure acute and chronic symptoms from those exposed to the contamination, the Australian Civil Aviation Safety Authority (CASA) established an Expert Panel on Aircraft Air Quality (EPAAQ). This Panel comprised members with expertise in aircraft engineering, occupational and environmental health, aviation medicine, toxicology and epidemiology to examine concerns about cabin air contamination.