The Atacama Desert in Chile is generally considered to be the driest place on Earth. The South American plateau receives little precipitation (about 15mm annually) and is virtually devoid of vegetation or animal life as a result, with humidity reaching just 10 per cent.
In a business class cabin, the average humidity is 7 per cent. In other words, it's drier than the driest place on Earth.
The arid conditions arise because the outside air that's drawn into the cabin is very cold - around -15°C - so it can't hold any moisture. As cabin air is also frequently refreshed (roughly every two minutes) the small amount of moisture that's generated is also filtered out very quickly.
Most humidity in the cabin actually comes from passengers via exhalation. The most humid part of a plane is therefore in economy (around 12 per cent), with premium cabins suffering more. First class passengers wither in around 5 per cent humidity, while the cockpit and crew rest areas suffer from the lowest levels, with just 2 per cent humidity.
"Your body dehydrates quickly when you're exposed to such an environment,” says Ola Haggfeldt, chief commercial officer at CTT Systems AB, a Swedish company that specialises in aircraft humidity. "You're basically losing 70 grams of water every hour, so even if you're drinking water, you're going to dry out."
We're all aware of feeling parched and dehydrated on a long-haul flight, disembarking with flaky skin and bloodshot eyes more suited to a Halloween costume, but the lack of humidity has more serious effects than personal aesthetics and comfort.
"From a health perspective, what happens is you dehydrate your mucus and respiratory system," Haggfeldt explains. "Typically, how the immune system works is if you catch a virus or bacteria, your mucus basically traps it and your stomach acid kills it. When you're dried out, this doesn't happen. So, while you don't immediately get sick because of a lack of humidity, your chance of getting sick increases quite significantly."
[https://cdn.magzter.com/1450191940/1685026392/articles/_6E0fEno21685086914525/0081165186.jpg]
It's the same reason why more people get sick in the winter - the cold, dry air suppresses your immune system, making you more susceptible to airborne bugs. Aircraft these days are equipped with hospital-grade HEPA filters, which kill 99.9 per cent of any airborne pathogens, so you're unlikely to contract anything mid-flight. But the second you step into a busy airport or a crowded bus, your wrecked immune system leaves you vulnerable.
Aside from your health, quality of sleep is also affected, says Haggfeldt: "Studies have shown you sleep better when you breathe better, and you breathe better when there is natural moisture in the air. Having better sleep on an aircraft also means less negative effects from jet lag."
Humidity also plays a role when it comes to inflight dining. Around 80 per cent of your taste perception comes from scent and odour, yet your sense of smell is greatly reduced in dry conditions. As anyone who's ever had a cold can attest: if you can't smell something, you can't really enjoy it. If humidity was improved in cabins, it would also improve the enjoyment of food and wine, which airlines invest a lot of time and effort into.
[https://cdn.magzter.com/1450191940/1685026392/articles/_6E0fEno21685086914525/6680070061.jpg]
RELATIVE HUMIDITY
Average cabin humidity without active humidification on long-haul flights
[https://cdn.magzter.com/1450191940/1685026392/articles/_6E0fEno21685086914525/AuEPrVUOj1685087102499.jpg]
Liquid assets
It's a no-brainer that more humid cabins would be more humane, so why aren't humidifiers a staple on modern aircraft?
Common issues with cabin humidifiers relate to the increased onboard weight as well as the unwanted byproduct of increased condensation, which can cause corrosion or mould and can also get into the aircraft's intermediate spaces and potentially cause issues with things like the electrical systems. However, newer technology, such as that produced by CTT, offers a tandem dehumidifying effect to reduce these unwanted side effects, while increasing humidity for the cabin.
Another issue, as with everything, is cost and demand. One barrier to airlines investing in more humid cabins is that it's hard to market something you can't see, or necessarily even sense.
"When airlines configure a new cabin interior, they start with a bag of money and a wish list - we want those seats, that galley, that fabric. Of course, they're going to exceed that bag of money, and then have to start taking away. What do they take away? The things you cannot see," says Haggfeldt.
"When you walk into a premium cabin, in a glance you can take it in and think 'Wow this looks really nice, but how do you present humidity? It's a feeling. The strange thing is everyone knows the cabin air is dry. If you fly a lot, you really do feel the difference - you don't need to take out your contact lenses, you don't get sick, you feel more comfortable, but not much has been done about it.
"It's like pressurisation in aircraft. Now on the 787, A350 and 777X, there is a higher pressure in the aircraft to get closer to the pressure on Earth, which is more comfortable. But getting to that step has taken many years, with manufacturers having to build a fuselage that could withstand the increased pressure and so on. So, it's going to take time."
However, things are starting to change. On private jets, where humidity is more of a problem due to the low passenger load, and passenger expectations are higher, onboard humidifiers have started to become the norm. Commercial airlines have also started adding humidifiers to the cockpit and crew rest areas, which are now prevalent on aircraft including the A380, A350 and Boeing 787.
But what about in the passenger cabin? China Southern was the first airline to select an inflight humidification system for its A350 business class cabins, delivered in 2019, while Emirates and ANA plan to fit humidifiers on the Boeing 777X, and Lufthansa has requested humidifiers for its first class cabin on the A380.
"There is also a big Australian carrier (we can't officially say who) that has selected it to debut on a coming project. Once these early adopters get it out there, I think it's going to influence a lot of others," says Haggfeldt. Premium cabins are most likely to be the beneficiaries of new humidifying technology (not least because they are the most in need), but the positive is that even if just the front of the plane was given more moisture it would affect the entire aircraft, meaning all passengers would reap the benefits.
[https://cdn.magzter.com/1450191940/1685026392/articles/_6E0fEno21685086914525/uFO8e4V4x1685087156988.jpg]
Hot and bother...
In a business class cabin, the average humidity is 7 per cent. In other words, it's drier than the driest place on Earth.
The arid conditions arise because the outside air that's drawn into the cabin is very cold - around -15°C - so it can't hold any moisture. As cabin air is also frequently refreshed (roughly every two minutes) the small amount of moisture that's generated is also filtered out very quickly.
Most humidity in the cabin actually comes from passengers via exhalation. The most humid part of a plane is therefore in economy (around 12 per cent), with premium cabins suffering more. First class passengers wither in around 5 per cent humidity, while the cockpit and crew rest areas suffer from the lowest levels, with just 2 per cent humidity.
"Your body dehydrates quickly when you're exposed to such an environment,” says Ola Haggfeldt, chief commercial officer at CTT Systems AB, a Swedish company that specialises in aircraft humidity. "You're basically losing 70 grams of water every hour, so even if you're drinking water, you're going to dry out."
We're all aware of feeling parched and dehydrated on a long-haul flight, disembarking with flaky skin and bloodshot eyes more suited to a Halloween costume, but the lack of humidity has more serious effects than personal aesthetics and comfort.
"From a health perspective, what happens is you dehydrate your mucus and respiratory system," Haggfeldt explains. "Typically, how the immune system works is if you catch a virus or bacteria, your mucus basically traps it and your stomach acid kills it. When you're dried out, this doesn't happen. So, while you don't immediately get sick because of a lack of humidity, your chance of getting sick increases quite significantly."
[https://cdn.magzter.com/1450191940/1685026392/articles/_6E0fEno21685086914525/0081165186.jpg]
It's the same reason why more people get sick in the winter - the cold, dry air suppresses your immune system, making you more susceptible to airborne bugs. Aircraft these days are equipped with hospital-grade HEPA filters, which kill 99.9 per cent of any airborne pathogens, so you're unlikely to contract anything mid-flight. But the second you step into a busy airport or a crowded bus, your wrecked immune system leaves you vulnerable.
Aside from your health, quality of sleep is also affected, says Haggfeldt: "Studies have shown you sleep better when you breathe better, and you breathe better when there is natural moisture in the air. Having better sleep on an aircraft also means less negative effects from jet lag."
Humidity also plays a role when it comes to inflight dining. Around 80 per cent of your taste perception comes from scent and odour, yet your sense of smell is greatly reduced in dry conditions. As anyone who's ever had a cold can attest: if you can't smell something, you can't really enjoy it. If humidity was improved in cabins, it would also improve the enjoyment of food and wine, which airlines invest a lot of time and effort into.
[https://cdn.magzter.com/1450191940/1685026392/articles/_6E0fEno21685086914525/6680070061.jpg]
RELATIVE HUMIDITY
Average cabin humidity without active humidification on long-haul flights
[https://cdn.magzter.com/1450191940/1685026392/articles/_6E0fEno21685086914525/AuEPrVUOj1685087102499.jpg]
Liquid assets
It's a no-brainer that more humid cabins would be more humane, so why aren't humidifiers a staple on modern aircraft?
Common issues with cabin humidifiers relate to the increased onboard weight as well as the unwanted byproduct of increased condensation, which can cause corrosion or mould and can also get into the aircraft's intermediate spaces and potentially cause issues with things like the electrical systems. However, newer technology, such as that produced by CTT, offers a tandem dehumidifying effect to reduce these unwanted side effects, while increasing humidity for the cabin.
Another issue, as with everything, is cost and demand. One barrier to airlines investing in more humid cabins is that it's hard to market something you can't see, or necessarily even sense.
"When airlines configure a new cabin interior, they start with a bag of money and a wish list - we want those seats, that galley, that fabric. Of course, they're going to exceed that bag of money, and then have to start taking away. What do they take away? The things you cannot see," says Haggfeldt.
"When you walk into a premium cabin, in a glance you can take it in and think 'Wow this looks really nice, but how do you present humidity? It's a feeling. The strange thing is everyone knows the cabin air is dry. If you fly a lot, you really do feel the difference - you don't need to take out your contact lenses, you don't get sick, you feel more comfortable, but not much has been done about it.
"It's like pressurisation in aircraft. Now on the 787, A350 and 777X, there is a higher pressure in the aircraft to get closer to the pressure on Earth, which is more comfortable. But getting to that step has taken many years, with manufacturers having to build a fuselage that could withstand the increased pressure and so on. So, it's going to take time."
However, things are starting to change. On private jets, where humidity is more of a problem due to the low passenger load, and passenger expectations are higher, onboard humidifiers have started to become the norm. Commercial airlines have also started adding humidifiers to the cockpit and crew rest areas, which are now prevalent on aircraft including the A380, A350 and Boeing 787.
But what about in the passenger cabin? China Southern was the first airline to select an inflight humidification system for its A350 business class cabins, delivered in 2019, while Emirates and ANA plan to fit humidifiers on the Boeing 777X, and Lufthansa has requested humidifiers for its first class cabin on the A380.
"There is also a big Australian carrier (we can't officially say who) that has selected it to debut on a coming project. Once these early adopters get it out there, I think it's going to influence a lot of others," says Haggfeldt. Premium cabins are most likely to be the beneficiaries of new humidifying technology (not least because they are the most in need), but the positive is that even if just the front of the plane was given more moisture it would affect the entire aircraft, meaning all passengers would reap the benefits.
[https://cdn.magzter.com/1450191940/1685026392/articles/_6E0fEno21685086914525/uFO8e4V4x1685087156988.jpg]
Hot and bother...
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Business Traveller Uk (Digital) - 1 Issue, June 2023