Peter wrote:
What particle size is caught by HEPA filters?
Viruses are mostly 50-150nm across.
Some opinions of this are around. This one probably puts it into perspective:
Impeccably efficient, the HEPA filter kills bacteria, fungi, and virus clumps. What it does not protect against, however, is being sneezed on by a sick passenger or touching an infected tray table.
So basically, HEPA filters will do a pretty good job on the air itself, making airliner air most probably a lot safer as air in chicken batteries mass offices or let alone trains or worse underground trains.
What filters won’t do, regardless of particle size, is to protect you against the usual unhygienic behavior of fellow cattle passengers.
Hence, the idea of most airlines to make pax wear masks throughout the flight and lock the toilets may well do the trick, even though I wonder how they wish to enforce the latter without some very nasty surprises on the seats or below… additionally to that it may be a very good idea to carry desinfectant towels and use them liberally.
From above:
According to the Environmental Protection Agency, HEPA filters catch “at least 99.97 percent of dust, pollen, mold, bacteria, and any airborne particles.” Commonly used in spaces that require high sanitary standards, such as hospitals, the filter has been built into airplane cabins since the 1980s.
99.97% is meaningless. It’s like saying that when I drive to work I avoid hitting 99.97% of the other cars.
The Centers for Disease Control and Prevention (CDC) explains that airplanes built after 1980 recirculate up to 50 percent of cabin air by combining the internal air with external air, filtering the supply through the HEPA filter. On average, this process occurs every three minutes. Only particles smaller than 0.3 microns manage to pass through the device, meaning that the vast majority of contaminants are completely removed.
0.3 microns is 300nm – more than 2x the size of the biggest viruses, so basically ineffective, unless the virus is coagulated into something bigger and that gets caught.
There is a view that viruses rarely free-float and are only ever found in moisture droplets.
without some very nasty surprises on the seats or below…
I know a guy who services airliners and apparently people do poo on or under the seats 
Not meaningless. It’s probably the case that if you are exposed to large doses of the virus you get sicker than if you are exposed to smaller doses, even if you do get sick. Each viral particle has a particular chance of causing an infection, so if you are exposed to a moderate number of particles, the sieve may reduce their number enough to avoid the wearer getting sick at all.
My understanding of the filters is that they work more by electrostatics than as a sieve; if you imagine the viral particles as lots of little polystyrene beads, they will get caught on the fibers even if they are big enough to get through the gaps.
Peter wrote:
There is a view that viruses rarely free-float and are only ever found in moisture droplets.
Well, that is what I understand as well and why most airlines impose masks so passengers won’t let those droplets go free. @kwlf explains it better how these things work but I have to say, my larger concern than the cabin air itself would be the proximity to unknown people. Still I would think the situation in airliners will be better than in trains or busses where people do a good impression of a sardinecan. And what I hear from bording / debording procedures (one row at a time e.t.c. so quite long) I think it will be better than with other means of transport.
Silvaire wrote:
I’d prefer to pay cash for any medical care under maybe $10K per year, as would a whole lot of other people. Unfortunately, the changes in US health care law a few years ago made this mostly illegal, now you are forced to buy insurance with a small deductible.
I remember the discussion well when Obamacare came into existence (actually if I remember right it should be called “Romney Care” as it was Mitt Romney (Rep) who came up with the principle of what became Obamacare while governor. I had the pleasure of meeting him once at Gettysburg, a very fine gentleman).
Actually, it mirrors pretty much what we have in Switzerland. Since ever, Switzerland’s health insurance was responsibility of each citizen, so it is an open market for insurance. Normal and now obligatory category is basic care, which since a few years everyone must have. It is still your responsibility to find an insurance and get insured, but the government will make you if you don’t. If you can’t pay for it, social services will. Also no health insurance may refuse you for basic care cover and tarifs are within a rather close range.
Within basic care everything you normally need is included, all surgery, doctors visits, most medicine. There are some things which need extra insurance, which you may take out or not. Most of us do have travel insurance, some take out complimentary medicine such as TCM, Acupuncture, e.t.c., some have higher levels of hospital care up to fully private insurance which means single room and care by the top shots of doctors. However, also basic care patients get access to those if the need arises, but they will initially be treated by whoever is available. Each model has a small part which you have to pay yourself, up to a upper limit of between 500 CHF to about 3000 CHF from where on everything is covered.
Within basic care, there are clear cost models set up between health insurances and health service providers with the goal of keeping costs lower without loosing quality. e.g. the use of original vs generica medicines and almost everything is defined via tarif points so within basic care the same treatment always costs roughly the same, no matter in which institution it is administered.
Basic insurance became obligatory some 20-30 years ago, basically the same goal that Romneycare had, to provide basic healthcare for everyone. The logic behind that was and is, that by law hospitals are not allowed to refuse treatment to anyone needing it, but before obligatory basic healthcare often faced the situation where uninsured people would not or could not pay, basically the very situation the US is notorious for. Personally, I find the regulation here makes a lot of sense. As with any healthcare system there are ups and downs, but personally I find it very reassuring to know that whatever happens, I will not have to worry how to pay for my doctors bills, nor will I bancrupt my family in case I have an accident or God forbid get cancer or something like this.
When i saw cases like former UAL Captain Al Haynes having to collect money for his daugther to get life saving treatment e.t.c then I figure something is wrong. Not because of who is was, but retired airline captains are not really lower income class and I can just imagine how many people will die because they don’t dare to get treatment. If that is the case for COVID 19 to explode like that, then the case for compulsory basic insurance has been made yet again. The Affordable Healthcare Act as I understand it still does not guarantee basic insurance for everyone, with the result that lots of people still can not get insured or worse can get no treatment. In a nation like the US, I find this unacceptable.
Perfect is the enemy of good – something I think Germanic countries have never properly understood.
Janitors that empty the trash from my office can get exactly the same health insurance I’ve described, better than anything in Europe particularly in terms of its flexibility and options, and it covers all members of their immediate family. The key issue is somebody in the family has to work to get it. There’s a reason why until the recent arrival of Coronavirus from Europe that US unemployment was so low. In time that situation will reestablish itself, and government control over the maintenance of my body will not occur – including maintaining my right to buy what products I want in the commercial market, or not to do so.
As a backup to the above, generally at the US state level, people who ‘fall between the cracks’, have no money or are illegally in the country do in fact get treated but its not a comfortable situation for them. Nor should it be. Perfect is the enemy of good.
Romney has the quality that many Mormons have of building community, like him they are also very often aggressive businessmen outside of their community. I agree that he might have been good if elected – I voted for him.
Silvaire wrote:
The key issue is somebody in the family has to work to get it.
So I understand from many discussions I’ve had with people who live in the US. I understand this is a grown and proven system in most cases but you end up without health care the day you loose or quit a job, even in between jobs and will have to renegotiate new conditions and all with the provider of your new job. Seeing that changing jobs in the US is much easier and also more common than e.g. here, I wonder what interest the employer actually has having to meddle into employees healthcare? How do self employed people handle this?
Our healthcare insurance is totally independent from the employer even if some of them cover some part of the cost. Changing jobs won’t affect your healthcare cover in any way, most people stay with an insurance for life as benefits you get as a long year customer are not necessarily transferred to a new insurer.
If Americans are so interested in personal freedom, I would be more concerned about my employer being involved in my healthcare insurance, knowing my medical files than the government simply obliging me to take out basic health insurance by law.
Mooney_Driver wrote:
I understand this is a grown and proven system in most cases but you end up without health care the day you loose or quit a job, even in between jobs and will have to renegotiate new conditions and all with the provider of your new job.
When you get a new job your don’t “negotiate conditions”, you just sign up and get a card in the mail from the insurance company. My company has three different plan choices, at three different cost levels. I buy by far the most expensive choice and its under $300 off the gross amount every two weeks for my wife and I, and not taxed. I could cut that amount substantially by signing up for a plan that requires me to name a primary care doctor as a gate keeper for treatment – but I have no interest in that.
My wife has no insurance coverage from the small business she works for but she doesn’t need it – we are a self created team at least until we reach 65 
when we will be independently eligible for Medicare. If I lost or wanted not to buy coverage, she might very well get a job with the primary goal of providing it, with cash payment from the job being secondary. In addition to encouraging people to work, encouraging them to create families and work together is also a good thing.
Mooney_Driver wrote:
How do self employed people handle this?
They buy insurance in the open market. Many were quite annoyed when forced to buy more coverage than they needed or wanted to buy.
Mooney_Driver wrote:
If Americans are so interested in personal freedom, I would be more concerned about my employer being involved in my healthcare insurance
You can change employers in a day, you can’t change national governments while staying in the same country. There are related arguments about state versus national involvement in health care, because in the US you can move between states without any notification or paperwork except for the new state eventually getting your annual tax return and knowing you’re out there somewhere.
Employers have no access to your healthcare records. What is concerning however is the ability of health insurance companies to trade data on individuals. This is supposed to be limited by law but that does not seem to me to be effective. Another fight for the future.
Peter wrote:
0.3 microns is 300nm – more than 2x the size of the biggest viruses, so basically ineffective
I’ve been reading on HEPA filters the last few weeks. The word is that they are measured at effectiveness at 0.3 microns because that’s what they are least effective at filtering. Both bigger and smaller particulates are filtered more effectively. I’ve been reading that our intuition of a filter working like a sieve (through “straining”) breaks down with particulates smaller than about 1 µm (1000 nm). Smaller particulates are caught by interception, and once you get below 300 nm, by diffusion because they exhibit brownian motion.
This entry, part a “clean air” blog run by people that runs loads of tests (and manufacture low-cost HEPA filter units, one model of which is sold in Europe rebranded under an Auchan house brand), contains explanations and pictures.
“Intuitively”, I quite like that blog. They test, and report test results. With figures.
These airliner filters we are talking about…are they the same as the ones they were using last year??
As someone who travelled frequently for work, I would say that for sure I have picked up colds/flu etc on flights/airport.
Now, whether this is the airport crowding everyone up in busses/departures/security etc or in the actual aeroplane…
