Cupe 4070
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In Solidarity

In Solidarity With CUPE Local 4088


Toxic Fumes

The Air We Breathe

Airplanes need to pressurize the interior cabins to allow passengers to breathe normally. Most jet-propelled airplanes achieve this pressurization by “bleeding” a small percentage of highly pressurized air from within the engines into the air circulation of the internal cabin.

Bleed air is supposed to be fresh, clean, air taken from the compressor section of the engine before it is mixed with fuel or exhaust gasses, however, it isn’t always “clean.”

Even engines under the strictest of maintenance schedules can malfunction or break down. Additionally, the seals inside engines can lead to low doses of exposure because of the way many of them are designed.

Synthetic lubricants with special heat-resistant additives are used to keep moving parts in a jet engine at a cool operating temperature. If there is a malfunction, the lubricating oil or other chemicals such as de-icing fluid can be pulled into the bleed air and fed directly into the aircraft cabin.

At elevated temperatures, such as those found inside a jet turbine, the additives in these products can degrade and become converted into a fine mist or fumes that becomes part of the air in the cabin. There is no filtration equipment currently onboard standard commercial aircraft designed to remove these toxic fumes before or after they enter the cabin.

It has been known for more than 60 years that the malfunctioning of an engine can introduce unwanted chemicals into the cabin and result in acute exposure. This is commonly known as a “fume event.”

Health Issues Associated With On-Board Fume Events

There is significant evidence showing that exposure to chemicals through the bleed air is a hazard. In fact, any symptoms that might develop can be clues about the type of chemical that has been released into the air. It is important to document and report all symptoms as this may help substantiate the case that an exposure did in fact occur. This is especially important if additional health concerns arise in the future.

When Cabin Crew Members are exposed to hydraulic fumes, they often have a cough and experience burning or irritation of eyes, nose and upper airways, breathing difficulties and feelings of tightness in their chests.

People who breathe oil fumes typically report fewer respiratory issues and more cognitive impairments such as blurred or tunnel vision, headache or light headedness, dizziness, difficulty concentrating, nausea and vomiting. Another common symptom is a metal taste in the mouth, which may last well past the time of exposure. While many of these symptoms are common, not everyone reacts in the same manner, or at the same level.

Longer-term effects of exposure to contaminated bleed air may include damage to the respiratory and central nervous systems, impaired memory and cognitive function, weakened immunity, cardiovascular disorders and possibly cancer.

Though Cabin Crew Members and Pilots are most affected due to higher levels of exposure, our guests are also at risk. Some passengers who are more sensitive to chemicals and toxins may fall ill. Finally, any cognitive impairment of flight crew due to toxic fumes decreases their performance and can jeopardize overall airline safety.

Identifying Fumes Onboard

Airlines are not required to monitor the cabin air for chemical content. Because of this, it can be very difficult to know what is in the air. Still, there are two things to note when you suspect an onboard fume event: source and odour.

The source of the fumes provides one clue. Flight attendants should attempt to determine where the smell is coming from (for example, vents or from something inside the cabin).

The specific type of odour is another clue. As previously mentioned, various sources have different smells.  

For example, imagine a scenario where the fumes appear to be coming from the vents. There is no obvious fume source in the cabin and the fumes became apparent during climb or descent, or when the auxiliary power unit is run on the ground. In this case, a fume event would be suspected, and the pilots and maintenance workers should investigate the presence of oil or hydraulic fumes in the air supply system. It should be noted that this  event is different than the “diesel” smell that frequently occurs at the start-up of the engines.

While not all odours on an airplane are hazardous, it is crucial that airline crew, both Pilots and Cabin Crew Members, understand what to look for and how to report concerns to ensure flight safety and the health of all on board.

As a guideline from the International Civil Aviation Organization (ICAO) notes: “often, oil fumes do not smell like oil.” Instead, they are typically described as smelling like dirty socks/smelly feet, foul, or musty. Hydraulic fluid often has a distinctive and recognizable odour that is often described as acrid.”

What You Should Do If You Suspect Exposure To A Fume Event On-Board

If you are experiencing symptoms of exposure, immediately seek medical assistance.

Report the health and safety concern both to the company (via AQD) and to your union representatives on the Health and Safety Committee. Even if you are not experiencing symptoms of exposure, you should notify your primary care physician, and provide as much information as possible to them, bearing in mind that most physicians are not familiar with the effects of toxic fumes on board an aircraft.

If fumes came from the vents and odours or symptoms are consistent with oil or hydraulic fumes, then give the doctor the safety data sheets or at least the names of the relevant products. (Mobil Jet Oil II, or Skydrol hydraulic fluid, for example). These can be obtained directly from the company who must provide them if it is suspected that you may have been exposed to a toxic breathable substance. Your health and safety committee can help if needed.

It is also imperative that you complete a worker’s compensation form for the provincial compensation board under which you are based (such as WSIB, CSST, Worksafe). Remember that the long-term effects of fume event exposure are still not completely understood. Even if you are not experiencing significant symptoms now, CUPE recommends following procedures to protect against future losses. Remember that by reporting a workplace illness or accident to the worker’s compensation board, you aren’t committing to actually taking time off on workers compensation. You are contributing to a permanent record of your work-related health events with the government, which may benefit you down the line.

REMEMBER: If you are concerned about a health and safety risk, you have the right, by law, to refuse unsafe work. If you have any questions regarding your right to refuse unsafe work, please immediately contact one of your health and safety Committee members, or any Union representative.

Click HERE to learn more about your right to refuse dangerous work.

You can email your Health and Safety committee at

In Solidarity,

CUPE Local 4070