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How to stay ahead of the problem of poor cabin air filtration?

There is not much that can ruin a flight experience like a tenacious foul-smelling odour which persists throughout the flight. At best, it can lead to passenger complaints and loss of consumer brand trust. At worst, it can cause fear and anxiety amongst passengers and crew as to their safety within the aircraft.

Most airlines take cabin air filtration very seriously. But there is a contentious debate regarding whether there is any long-term danger posed by poor cabin air quality. The fact remains that there is no scenario where an airline will experience a positive net outcome from having poor aircraft cabin air filtration.

How can you maximise cabin air quality and reduce odour complaints? Contact us to find out!

Ideally, cabin air quality shouldn't be something your passengers notice. When they do, it can be costly. If you'd like to ensure your cabin air doesn't result in complaints, fill in your information below and a Satair expert will assist you shortly.

The good news is that with a little understanding of the problems and available solutions, airlines can help alleviate the concerns of both passengers and crew. In this article, we will be looking at the various origins of cabin air quality events and defining the solutions that can mitigate them.

Understanding the various nomenclatures

You don't have to dig very far to find yourself awash in a sea of terminologies. Ones that all seem to mean the same thing–or are different by only a fraction of a degree. We are referring to the classification of smells or odours found in aircraft cabin air.


According to John Vinson, Pall Product Manager, Americas, "Fume Events are more serious than 'Transient Odours,' when it comes to safety. 'Fumes' encompass more than just 'Odours'. 'Transient odour' is a description usually interchangeable with 'nuisance odours because it can be any number of things."

"Without real-time accurate and consistent identification of odours, operators are forced to rely on flight crew descriptions, often leading to many potential sources. Experienced technicians are then counted on to identify and recreate the odour for confirmation. With an unidentifiable transient odour, one thing can lead to another, and soon you're replacing an engine on the aircraft, a rare but costly solution."

Poor cabin air quality can lead to hidden costs. Find out how.

1. Transient or Nuisance Odours

This terminology is often used within the aviation industry to classify any cabin odour that has elusive or hard-to-identify origins but that is not inherently dangerous. 

2. Fume Events

Used by the industry to describe odours that originate from engine bleed air—more specifically, when oil or hydraulic fluid is vaporised and introduced into cabin air. The percentage of fume events that occur during an aircraft's lifecycle is still hotly disputed, which makes mitigation difficult.

3. 'Toxic' fume events & toxic air events

Often used by popular media, news, and advocacy groups to sensationalise the danger of fume events.

4. Cabin air quality events (CAQEs)

A classification introduced by IATA to define the majority of cabin odour events. The designation refers to minor odour events from toilets, passengers or foreign sources, as well as more serious events like persistent air contamination, resulting in symptoms or illness.

Understanding the potential sources of odours.

Creating a broader awareness of what commonly causes odours, and understanding simple mitigation measures, can significantly reduce the risks that they pose.

1. Oil and hydraulic-fluid leakage

During flight, bleed air coming in through the engine can range from 200C° to 250C° (392F° to 482F°). Any leakage originating from the engine's oil-bearing seals or hydraulic system reservoirs can lead to hazardous fluids becoming instantly vaporised and mixed with the recirculated cabin air.


2. Contaminates from the Auxiliary Power Unit (APU)

For most commercial aircraft, the APU is primarily used for starting up the main engines. Once that has occurred, though, their purpose is to maintain the cabin and cockpit air conditioning. Should the APU begin to fail, any smoke, vapour, or odour can find its way into the recirculated cabin air.

"The APU has been known to ingest hydraulic fluid dripping from the underbelly of the aircraft, driven into the intake by the aircraft moving forward or the APU sucking it in," states Vinson. "The intake of the APU at the bottom of the aircraft is often mentioned as the main reason, specifically on the A320. APU seals around the intake and seals in the APU have also been mentioned as a source of contaminate."

3. People, people and more people

Most commercial aircraft have a passenger capacity between 175 and 540. That's about 175 to 540 different opportunities for bacteria, odours, viruses and particulates to mix with the cabin air. While this may seem daunting, the truth is, the level of air contamination would be the same if those same people were waiting at the airport.

In IATA's medical manual, they state,"With the current body of knowledge, aircraft cabin air quality during normal operation is perfectly acceptable and often better than other well-accepted indoor environments."

Aircraft cabin air filtration can mitigate the issue

HEPA (High-efficiency Particulate Air) filters have been the industry standard on most aircraft since the 1980s. Initially developed for the medical industry, HEPA filters are capable of removing 99.97% of airborne particulates measuring 0.3 microns.


That said, commercial HEPA technology is nearly seven decades old. Additionally, odour inducing particles commonly fall under 0.3 microns. This can lead to "Transient" odours finding their way into the cabin air and potentially causing fear of danger from passengers and crew.

Fortunately, newer filter technologies utilising activated carbon filters, such as Pall's newest line of A-CAF (Advanced Carbon Air Filter), offer a higher filtration percentage, in addition to many other positive features.

"A-CAF filters will reduce the fears and complaints from passengers and flight crew, states Blake Andrews, Head of Pall Aerospace and Engine Programs, Product Management at Satair. "The carbon filtration technology has the proven ability to capture and contain dangerous airborne chemicals which may be present."

"A-CAF filters will remove non-persistent odours from the cabin 3 to 4 times faster than a HEPA cabin air filter. When events quickly dissipate, passengers and crew promptly go back to being more comfortable."

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About this blog

This blog is driven by Satair Marketing & Communication with input from both internal and external contributors.