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Frequently Asked Questions

Where does the air supply come from on a passenger jet aircraft?

On all currently flying commercial jet aircraft (except the Boeing 787), the breathing air supply is taken, unfiltered, from the compression section of the engines in a process known as 'bleed air'.

How does the air become contaminated with toxic chemicals?

For over 60 years, the aerospace industry has known that this ‘bleed air’ becomes contaminated with toxic chemicals released when the lubricating oils are heated; thus contaminating the ‘bleed air’ (the air we are supplied to breathe) in an unpredictable quantity.

How could contaminated air potentially affect me?

Contaminated air contains chemicals known to be toxic, such as organophosphates. Scientific studies have found a clear pattern of acute and chronic symptoms ranging from headaches and dizziness to respiratory and neurological problems.

Why haven't I noticed any strange smells on the plane before?

Contaminated air is made up of a complex cocktail of chemicals, many of which are odourless and colourless. This means contaminated air is almost completely undetectable to someone who does not know the signs (similar to carbon monoxide). Some chemicals will have a noticeable odour above a certain concentration or it may be very faint. It is often described as a "dirty sock" or "wet dog" type of smell. However, even if recognised, a person's sense of smell will often become desensitised in less than two minutes.

What if I'm pregnant? Am I more at risk?

Exposure to contaminated air will most likely impact individuals in different ways in both the short and long term based on a number of variable factors: levels and types of chemicals present during an exposure, previous exposure history to chemicals, genetic make-up, age, and medical condition. Engine oil manufacturers state that synthetic jet engine oils contain products which are 'a risk to infertility’.

Are the pilots and flight crew affected by contaminated air?

Perhaps the most vulnerable people are frequent flyers, including pilots and crews. Contaminated air has been known to significantly impair crews and even incapacitate pilots in flight. Safety investigators have been calling for detection systems to be fitted for over a decade.


An article written on contaminated air, published in a World Health Organisation journal, states: ‘This is a clear occupational and public health issue with direct flight-safety consequences.’

How can I protect myself?

The Boeing 787 Dreamliner does not rely on air that has been bled off of the engines to supply the cabin with breathing air. This makes the Dreamliner the safest jet to fly on, in relation to this issue.


There are different types of face masks available to purchase which may offer various degrees of protection. The real solutions, however, come with the airlines fitting detection and filtration systems to detect and prevent the breathing air from becoming contaminated.

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