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

[servodude]

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.

Bang on!
The relative cleanliness between the air at the input and output ports on an AC filter is a very good indicator of how well that filter works and not a whole lot else
- if it were otherwise you could stick someone in a high-end face mask on a treadmill in the corner of the room to do the job for everyone else

There are ways to measure how effective things might be in practice, but you'll not generally find them on a product datasheet

-sd

[Lootman]

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.

Bang on!

The relative cleanliness between the air at the input and output ports on an AC filter is a very good indicator of how well that filter works and not a whole lot else
- if it were otherwise you could stick someone in a high-end face mask on a treadmill in the corner of the room to do the job for everyone else

There are ways to measure how effective things might be in practice, but you'll not generally find them on a product datasheet

So where will we find that data then?

And given that in most cases passengers on a plane have had to have a very recent negative test result, surely that population are expelling less virus than another random selection of the same number of people in any comparable location?

[servodude]

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.

Bang on!

The relative cleanliness between the air at the input and output ports on an AC filter is a very good indicator of how well that filter works and not a whole lot else
- if it were otherwise you could stick someone in a high-end face mask on a treadmill in the corner of the room to do the job for everyone else

There are ways to measure how effective things might be in practice, but you'll not generally find them on a product datasheet

So where will we find that data then?

And given that in most cases passengers on a plane have had to have a very recent negative test result, surely that population are expelling less virus than another random selection of the same number of people in any comparable location?

Volumetric sampling using a diffusion tube would be one way to check.

The point about tests being required is salient though...
Do you think it's more likely that the SA test methods were poor and allowed many on a flight with COVID? or that they might contracted it on the flight?
https://www.aljazeera.com/news/2021/11/28/dozens-on-s-africa-flights-test-positive-for-covid-in-netherlands
- I'm leaning towards the latter given how good screening is in SA but we'd really need a deeper dive on the data to know either way with greater confidence

-sd

[gryffron]

Are the filters really that efficient when they don't seem to filter out the fume event chemicals (including organophospates) ?

They aren't designed to filter gaseous fumes. HEPA = High Efficiency Particulate Air. They're designed to filter solid matter. Specifically bacteria. Individual viruses are small enough to get through. But a covid virus can't "survive" on its own. The filters do quite a good job of stopping the small liquid particles in which covid "survives" and is spread.

Gryff

[murraypaul]

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 would think that by far the highest risk point in air travel will be queuing for security at the airport, with everyone mixed in so closely together.

Pilots and crew don't go through normal security queues.

Once you are on the plane, the risk should be lower than travelling on a bus or train.

[richfool]

As a postscript to my OP, another thought occured to me, - aren't the toilets on the plane going to be a potential covid transmission risk?

What with the queueing, one passenger following another in rapid succession, into a very confined space, where they then spend perhaps 5 minutes, and also the fact that passengers will undoubtedly be touching many surfaces in there.

[Spet0789]

As a postscript to my OP, another thought occured to me, - aren't the toilets on the plane going to be a potential covid transmission risk?

What with the queueing, one passenger following another in rapid succession, into a very confined space, where they then spend perhaps 5 minutes, and also the fact that passengers will undoubtedly be touching many surfaces in there.

Wear a decent mask, don’t touch your face, wash your hands (as I hope you always do!) when you leave the toilet.

Don’t panic!

[richfool]

As a postscript to my OP, another thought occured to me, - aren't the toilets on the plane going to be a potential covid transmission risk?

What with the queueing, one passenger following another in rapid succession, into a very confined space, where they then spend perhaps 5 minutes, and also the fact that passengers will undoubtedly be touching many surfaces in there.

Wear a decent mask, don’t touch your face, wash your hands (as I hope you always do!) when you leave the toilet.

Don’t panic!

On long haul flights the toilet trip could last longer than 5 minutes and would include brushing teeth amongst other things!

I had thought of holding my breath, but wouldn't be able to manage that long enough!

[dealtn]

As a postscript to my OP, another thought occured to me, - aren't the toilets on the plane going to be a potential covid transmission risk?

What with the queueing, one passenger following another in rapid succession, into a very confined space, where they then spend perhaps 5 minutes, and also the fact that passengers will undoubtedly be touching many surfaces in there.

Wear a decent mask, don’t touch your face, wash your hands (as I hope you always do!) when you leave the toilet.

Don’t panic!

On long haul flights the toilet trip could last longer than 5 minutes and would include brushing teeth amongst other things!

I had thought of holding my breath, but wouldn't be able to manage that long enough!

Yes it's a potential Covid risk, most things are. Do what you're comfortable with - including not going. But the risks are surely small. There are a large number of people working in the airline industry, and as far as I know they have the same toilet habits as the rest of us and will be using those toilets many more times than any of us as individuals who fly much less frequently. Has anybody spotted any Covid stories of how transmission rates are multiple times higher among cabin crew (let alone anything more scientific than media filler)? I certainly haven't.