It is possible according to government sources that one flight in 100 may suffer a "fume" event (contamination may even be more frequent), but it is accepted most events are never reported at all. Small amounts of contamination of the cabin air may not be detected at all. So it is likely that this problem is under reported due to a lack of awareness of the public, airline staff, and maintenance personnel. A contamination event may be detected by just a faint odor to the air but can also be a visible bluish haze or smoke in the cabin.
Jet engine oil is specially designed to withstand intense heat and extreme environment of these high velocity engines. The oil contains many toxic ingredients, including a organophosphate - Tricresyl Phosphate (TCP) which is added to engine oil as an anti-wear agent. It must be remembered that organophosphates are used in nerve agents. TCP is much more dangerous than first realized because it contains neutotoxic. isomers, tri-ortho-cresyl phosphate (TOCP), MOCP (mono-ortho-cresyl phosphate) and DOCP (di-ortho-cresyl phosphate). The mixture of chemicals in the aircraft engine oils are heated and vaporized producing a large list of other chemicals including carbon monoxide.
Because the airline passengers may not know they have been exposed, they may attribute these symptoms to some other illness. For mild exposures, the symptoms may resolve over time. After a large fume event the passenger may not feel any symptoms initially, but then later a few days after their flight they realize they are seriously ill. Symptoms may be short term or long term. Airplane staff and frequent airline travelers, because of the number of hours that they fly, may be exposed chronically through many smaller contamination events thus cumulatively causing a greater health risk. Unfortunately the debilitating effects of a major exposure to contaminated air can have long term health consequences. .With those suffering with the more severe neurological symptoms, permanent damage may have been caused. It is important to educate the public and medical clinicians about the problem. It is also extremely important to recognize the problem and to have a detection and filtration system for airplane cabin air to prevent exposure of the passengers and crew.