The report, compiled for an official investigation into the danger, says pilots suffer "alarming cognitive failures" - including being unable to remember vital instructions from air traffic control or if they had put down the wheels before landing - risking "substantial loss of life".
Last year, the Government admits, there were 10 "air-contamination incidents" on British Aerospace BAe 146 aircraft alone, leading transport ministers to ask the official Committee on Toxicity to investigate.
The Committee commissioned the report in March from Sarah MacKenzie Ross, a consultant clinical neuropsychologist and chartered clinical psychologist at University College London, after she had examined 27 affected pilots.
Most planes take in air for passengers and crew through their jet engines and pump it unfiltered into the cabin. Campaigners and pilot's representatives have long warned that it picks up chemicals en route, which endanger passengers and crew - and they are now being vindicated.
Professor Chris van Netten, an expert on cabin air at the University of British Columbia, said he had found one of the chemicals causing most concern - tricresyl phosphate - in every aircraft he had examined. He said that taking cabin air in through the engines is "asking for trouble".
The report says all but one of the pilots examined suffered "chronic health problems, including fatigue, sleep difficulties, fluctuating gastro-intestinal problems, numbness and tingling in fingers and toes, memory loss and word-finding difficulties.
Captain Colin Barnet-Higgins - a pilot who had to retire early on medical grounds after flying for 35 years for several airlines - told The Independent on Sunday he had suffered from fatigue and short-term memory loss. He said: "I know of about 20 to 30 pilots who have this sort of problem."
The report says: "These findings are of obvious concern, especially as they pose a risk to flight safety, and may be magnified under particular working conditions.
"Some of the pilots we examined reported alarming cognitive failures following exposure to contaminated air such as: being unable to retain, or confusing, numerical data and information provided by air traffic control regarding heading, altitude, speed; completing tasks in the incorrect sequence; setting the wrong cleared level for the aircraft to climb or descend; being unable to recall important matters such as whether the undercarriage has been raised or lowered."Reuse content