« A fume event occurs when bleed air used for cabin pressurization and air conditioning in a pressurized aircraft is contaminated by fluids such as engine oil, hydraulic fluid, anti-icing fluid, and other potentially hazardous chemicals. » (source)
Wikipedia does not explain how and why a fume event can occur, but notes:
(1) status quo
Given that bleed air is tapped at an early stage before coming into contact with fuel and thus cannot come into contact with fuel, why then can it come into contact with the other fluids quoted above ?
To avoid any potential contact with these fluids, couldn't it be tapped an an even earlier stage (in the front section of the engine) or rerouted/transported differently from the engine into the cabin? Isn't there any solution (other than bleedless aircraft) to eliminate the potential for both fume events (acute exposure) and long-term health effects (chronic exposure) for the cabin-crew and frequent flyers due to long-term exposure to minimal doses ?