Airliner air conditioning and circulation - does it remove covid viruses?

[richfool]

Does anyone know if the air conditioning/circulation system on modern airliners would remove/filter out viruses such as covid from the air, or simply recirculate them around the plane?

[PhaseThree]

The air you breath on a modern airliner is a mix of fresh air brought in from the outside and recirculated and filtered air from the cabin. The airlines claim the filtering will remove 99% of nasties before recirculation and that the air is changed 20-30 times per hour This makes the air supplied to the cabin pretty clean and healthy. Unfortunately this doesn't stop you catching Covid.

The problem is not with the air supply itself, the problem is with the other passengers immediately around you, any one of whom could be infected and exhaling virus rich air. You will be breathing this in along with the freshly scrubbed cabin air as social distancing is simply not possible.

Personally I am avoiding any and all mass transport systems at the moment.

[Lootman]

According to the study cited in this article, the air on planes is cleaner than in hospital operating theatres, due to the high efficiency air filters used on planes:

https://www.usatoday.com/story/travel/a ... 665469001/

I have flown long haul a few times in the last 20 months without worrying about it too much. I worry more about crowded conditions at airports and so take precautions.

[richfool]

Thank you both for the information.

I thought (had heard) that the AC system would be good and that the weakest links would be the proximity to other passengers, (which I pondered might be reduced by travelling business class where there is a greater degree of separation), and the general queuing and "herding" that takes place in the airport and upon boarding and disembarking.

[gryffron]

Yes, aircraft have long had good A/C systems with only localised air circulation and regularly replaced filters**. Because airlines didn't like all their passengers catching colds and flu long before covid was a problem. So on-board an aircraft is about as good as it gets for any crowded "indoor" environment. So the only risk are those sitting very close, or everyone you meet in the airport.

**The need for constant maintenance of high efficiency HEPA filters is why such filters are rarely found in buildings, and even less likely in schools. Aircraft are of course subject to constant maintenance, the a/c filters are just one more item on the checklist.

Gryff

[Hallucigenia]

Does anyone know if the air conditioning/circulation system on modern airliners would remove/filter out viruses such as covid from the air, or simply recirculate them around the plane?

They're pretty good, they're making 20-30 air changes per hour, via HEPA filters - it's been notable how there's been far fewer outbreaks linked to plane travel than you might expect, but I would still wear a mask :
https://www.nytimes.com/interactive/202 ... afety.html

However omicron does change the odds somewhat - and the IATA medical advisor makes the point about airports being higher risk than the plane :
https://news.yahoo.com/omicron-could-le ... 37493.html

There's also the impact of omicron on airline staff leading to cancellations, you can get an idea here :
https://uk.flightaware.com/live/cancelled/

[Lootman]

the weakest links would be the proximity to other passengers, (which I pondered might be reduced by travelling business class where there is a greater degree of separation), and the general queuing and "herding" that takes place in the airport and upon boarding and disembarking.

Flying in Business or First (where available i.e. mostly on airlines with a 4 or 5 star ratings from Skytrax) doesn't just give you personal space on the plane. At the airport you will also likely enjoy dedicated check-in, fastrak security checks and the ability to wait for your flight in an airport lounge rather than out in the terminal. In some cases you can board the plane via a different door with direct access from the airline lounge. It all helps.

It is a bit harder to maintain separation upon arrivals, depending on the airport.

The other factor to bear in mind is that many countries require proof of a a negative test result 24-72 hours before boarding the flight, which is checked mostly at the airline check-in desk, and I would assume that boarding is denied to those who cannot provide that. Proof of vaccination may also be requested. Note that the UK no longer requires a negative test before arriving in the UK for those who are vaccinated.

PS: If Covid was really a problem on planes, you would think that cabin crew would be dropping like flies. They are not and are regularly tested so the data should be good.

[Redmires]

According to the study cited in this article, the air on planes is cleaner than in hospital operating theatres, due to the high efficiency air filters used on planes:

Covid isn't the only concern. Other reports suggest that the air recirculation systems used in airlines can be contaminated by oil and fluid leaks.

A Los Angeles Times analysis of NASA safety reports from January 2018 to December 2019 identified 362 voluntarily-reported fume events, in which almost 400 pilots, flight attendants and passengers received medical attention.

https://en.wikipedia.org/wiki/Fume_event

[Mike4]

While we are all busy reassuring ourselves aeroplanes present no risk, it might be worth remembering the air travel industry is the reason we have this covid pandemic in the first place.

As John Campbell acerbically points out, it didn't get here by walking across from China. It came here in aeroplanes.

[Steveam]

Lootman wrote “PS: If Covid was really a problem on planes, you would think that cabin crew would be dropping like flies. They are not and are regularly tested so the data should be good.”

I’d be interested to hear where you got this information as I have a friend who is high up in HR of a major airline who tells me that this is a major issue but has not become a problem as there are many staff available.

Best wishes,

Steve

[csearle]

Lootman wrote “PS: If Covid was really a problem on planes, you would think that cabin crew would be dropping like flies. They are not and are regularly tested so the data should be good.”

I’d be interested to hear where you got this information as I have a friend who is high up in HR of a major airline who tells me that this is a major issue but has not become a problem as there are many staff available.

Best wishes,

I suspect that it is also something that airlines would be keen to keep under wraps, were it to be the case. C.

[UncleEbenezer]

Smoking is happily gone, but you can perhaps get a yardstick from the cocktail of perfume, aftershave and deodorant.

With the proviso that - like smoke to a smoker - you might be heavily desensitised to them if you encounter them regularly. And that it might be hard to distinguish from petrochemicals in the plane itself.

[Hallucigenia]

While we are all busy reassuring ourselves aeroplanes present no risk, it might be worth remembering the air travel industry is the reason we have this covid pandemic in the first place.

As John Campbell acerbically points out, it didn't get here by walking across from China. It came here in aeroplanes.

Yeah, but that's more a factor of them transporting people who are already infected, rather than being a major source of infection, which is what we're talking about here.

[richfool]

the weakest links would be the proximity to other passengers, (which I pondered might be reduced by travelling business class where there is a greater degree of separation), and the general queuing and "herding" that takes place in the airport and upon boarding and disembarking.

Flying in Business or First (where available i.e. mostly on airlines with a 4 or 5 star ratings from Skytrax) doesn't just give you personal space on the plane. At the airport you will also likely enjoy dedicated check-in, fastrak security checks and the ability to wait for your flight in an airport lounge rather than out in the terminal. In some cases you can board the plane via a different door with direct access from the airline lounge. It all helps.

It is a bit harder to maintain separation upon arrivals, depending on the airport.

The other factor to bear in mind is that many countries require proof of a a negative test result 24-72 hours before boarding the flight, which is checked mostly at the airline check-in desk, and I would assume that boarding is denied to those who cannot provide that. Proof of vaccination may also be requested. Note that the UK no longer requires a negative test before arriving in the UK for those who are vaccinated.

Yes, indeed. For the past 6 years I have invariably flown Business class on long haul flights, (with EVA and Thai [B777's], and Malaysian), and the seating separation in the business class cabins is quite good. My concern was that, if I was to do so again, whether the potentially contaminated air from the economy (coach) cabin, or wherever, would be recirculated and pumped into my area of the Bus class cabin. From what you describe, it sounds as if one should be reasonably safe, air filtration and circulation-wise, all other things being equal.

Yes, currently, most of the disincentive and hassle comes from the requirements, tests and documentation at each end and the possibility of them changing whilst one is in a foreign country.

[BobbyD]

Lootman wrote “PS: If Covid was really a problem on planes, you would think that cabin crew would be dropping like flies. They are not and are regularly tested so the data should be good.”

I’d be interested to hear where you got this information as I have a friend who is high up in HR of a major airline who tells me that this is a major issue but has not become a problem as there are many staff available.

Best wishes,

Steve

US airline JetBlue has cancelled almost 1,300 flights over the coming fortnight as the rapid spread of the Omicron variant wreaks havoc for airlines.

Airlines are struggling with the combination of harsh winter weather in some parts of the northern hemisphere and the spread of Omicron, which has caused surging Covid-19 case numbers in countries including the UK, France, Italy and the US.

US airlines in particular are struggling with the Omicron surge because many are running schedules at or near pre-pandemic levels. United Airlines on said Wednesday that 150 flights were cancelled because of Covid-19 staffing issues, and on Thursday it cancelled another 188. Delta Air Lines cancelled 87.

JetBlue’s cancellations will continue until 13 January.

“We expect the number of Covid cases in the north-east [US] where most of our crew members are based to continue to surge for the next week or two,” a JetBlue spokesperson said. “This means there is a high likelihood of additional cancellations until case counts start to come down.”

A United spokesperson said: “The nationwide spike in Omicron cases this week has had a direct impact on our flight crews and the people who run our operation.”

British airlines, on the other hand, had announced reduced schedules weeks ago because of low demand. British Airways has not been forced to cancel any flights at the last minute because of the spread of the variant, even though some workers are off sick. EasyJet also said it had not suffered from any staffing issues.

More than 4,700 flights worldwide that were originally scheduled for Thursday have been cancelled, according to FlightAware, a data company. More than half of those cancellations were confirmed only on the day. It added to almost 2,900 cancellations on Wednesday, the data showed.

- https://www.theguardian.com/business/20 ... 00-flights

So airlines are being hit, but some are finding it easier to cover because they had already cut services and so have a pool of underutilised air crew, whop presumably have also had lower exposure, to draw on.

[Lootman]

Lootman wrote “PS: If Covid was really a problem on planes, you would think that cabin crew would be dropping like flies. They are not and are regularly tested so the data should be good.”

I’d be interested to hear where you got this information as I have a friend who is high up in HR of a major airline who tells me that this is a major issue but has not become a problem as there are many staff available.

I suspect that it is also something that airlines would be keen to keep under wraps, were it to be the case. C.

Although the airline staff unions also seem to think the risk is low:

"The largest flight attendant union in the U.S. that represents United flight attendants among other airlines -- the Association of Flight Attendants-CWA, AFL-CIO -- says they've seen a little over 1,000 flight attendants across the industry contract the novel coronavirus. That's less than 1% of the roughly 120,000 flight attendants that were employed at the end of last year, according to the Bureau of Labor Statistics."

https://abcnews.go.com/Business/us-airl ... d=73149839

While we are all busy reassuring ourselves aeroplanes present no risk, it might be worth remembering the air travel industry is the reason we have this covid pandemic in the first place.

As John Campbell acerbically points out, it didn't get here by walking across from China. It came here in aeroplanes.

Yeah, but that's more a factor of them transporting people who are already infected, rather than being a major source of infection, which is what we're talking about here.

Agreed. Blaming air travel for Covid is like blaming baseball if someone gets murdered with a baseball bat.

According to the study cited in this article, the air on planes is cleaner than in hospital operating theatres, due to the high efficiency air filters used on planes:

Covid isn't the only concern. Other reports suggest that the air recirculation systems used in airlines can be contaminated by oil and fluid leaks.

A Los Angeles Times analysis of NASA safety reports from January 2018 to December 2019 identified 362 voluntarily-reported fume events, in which almost 400 pilots, flight attendants and passengers received medical attention.

https://en.wikipedia.org/wiki/Fume_event

But now you are talking about all safety risks from air travel rather than just Covid, which was the question here. And in general air travel is considered the safest form of public transportation. To be fair you should compare the safety risks of air travel with those involved in travel by bicycle, car, bus, train, ship etc., not that those provide a real alternative to air travel in most cases anyway.

[AlumniLawn]

Regardless of filtration efficiency, the virus in circulation will remain at steady state (with an ever so slight increase to account for the inefficiency of the filters) as the virus is being expelled at steady state by those who are infected for the duration of the flight.

But filtration will prevent a meaningful build up of virus.

[richfool]

For those who wish to digress onto discussing airline crew covid cases, the following, relating to Hong Kong and Cathay Pacific, may be of interest:

Hong Kong is one of the world's biggest aviation hubs but also has some of the strictest coronavirus regulations in the world. Two pilots tell the BBC how these rules are affecting their mental health and putting a strain on their personal lives.

"You're just in a perpetual state of quarantine."

Pierre*, a pilot with the city's flagship carrier Cathay Pacific, has spent almost 150 days in isolation this year alone, he says.

Though Hong Kong has recorded barely any local coronavirus cases in recent months, the city has imposed an extensive testing and quarantine regime, in line with mainland China's zero Covid policy.

Pilots are not exempted from these rules - which means they spend an exceptionally large portion of their time either working or in quarantine.

These tough measures start at the airport.

All international inbound travellers have to take Covid-19 tests on arrival at Hong Kong airport and quarantine even if they test negative. They need to wait for their test results - which are made available on the same day - before they can proceed with immigration procedures.

"[Aircrew] have been on an aeroplane for upwards of 25 hours, sometimes closer to 30 hours if there are any delays," says Clark*, another Cathay Pacific pilot.

"They have to sit on a plastic chair and can't sleep, waiting for the tests. The whole process takes about four hours from the time you've landed to the time you get home."

If they test negative, they get to go home - but they're still not free.

In the first three days after arriving in Hong Kong, aircrew must remain at home. They can only leave for a maximum of two hours a day, and only to get tested for Covid or for essential activities.

Crew members then have to "avoid unnecessary social contact" for a further 18 days and continue daily testing.

https://www.bbc.co.uk/news/business-59370672

[Redmires]

According to the study cited in this article, the air on planes is cleaner than in hospital operating theatres, due to the high efficiency air filters used on planes:

Covid isn't the only concern. Other reports suggest that the air recirculation systems used in airlines can be contaminated by oil and fluid leaks.

A Los Angeles Times analysis of NASA safety reports from January 2018 to December 2019 identified 362 voluntarily-reported fume events, in which almost 400 pilots, flight attendants and passengers received medical attention.

https://en.wikipedia.org/wiki/Fume_event

But now you are talking about all safety risks from air travel rather than just Covid, which was the question here. And in general air travel is considered the safest form of public transportation. To be fair you should compare the safety risks of air travel with those involved in travel by bicycle, car, bus, train, ship etc., not that those provide a real alternative to air travel in most cases anyway.

I know it's slightly off-topic but I was really questioning the statement that cabin air is cleaner than hospital operating theatres. Are the filters really that efficient when they don't seem to filter out the fume event chemicals (including organophospates) ?

https://www.bbc.co.uk/news/stories-51633897

[AlumniLawn]

Covid isn't the only concern. Other reports suggest that the air recirculation systems used in airlines can be contaminated by oil and fluid leaks.

A Los Angeles Times analysis of NASA safety reports from January 2018 to December 2019 identified 362 voluntarily-reported fume events, in which almost 400 pilots, flight attendants and passengers received medical attention.

https://en.wikipedia.org/wiki/Fume_event

But now you are talking about all safety risks from air travel rather than just Covid, which was the question here. And in general air travel is considered the safest form of public transportation. To be fair you should compare the safety risks of air travel with those involved in travel by bicycle, car, bus, train, ship etc., not that those provide a real alternative to air travel in most cases anyway.

I know it's slightly off-topic but I was really questioning the statement that cabin air is cleaner than hospital operating theatres. Are the filters really that efficient when they don't seem to filter out the fume event chemicals (including organophospates) ?

https://www.bbc.co.uk/news/stories-51633897

Aircraft have H13 HEPA filter (99.9% efficient) and operating theatre's generally have H14 HEPA filters (99.99% efficient). The critical difference is that an OT is a sterile(ish) area generating very, very little free particulate whilst an aircraft is full of particulate matter from fabric, skin, hair amd so on plus the residue of coughs and sneezes which are all in circulation until removed by the filtration system. The quality of air in an OT is infinately cleaner than that in an aircraft not due to the filters but due to the absence of generating detritus.