Air filtration systems do not reduce the risk of picking up viral infections, according to new research from the University of East Anglia.
A new study published today reveals that technologies designed to make social interactions safer in indoor spaces are not effective in the real world.
There was an item in New Scientist, perhaps last century, of an experiment done at a hospital’s ICU ( UK, iirc, the hospital had some kind of religious name, like St (somethingorother) ),
and that experiment tested whether patient-to-patient infections were affected by ionizers ( which charge the air, making particles in the air stick to surfaces, like walls, objects, whatever )…
That experiment had no effect in the control condition, but the ionizer-test condition reduced those infections down to ZERO.
No hospital with any reputation would dare use such “New Age woo”, of course, no matter that evidence, combined with the Hippocratic Oath ( 1st do no harm! ), should oblige its use.
Bah.
I couldn’t find much of anything through DuckDuckGo.com
and Scholar.Google.com had stuff that wasn’t what I was trying to find,
and normal google had this
Anyways, according to the NO cases of inter-patient infection that was reported in the study I remember, it should have been made globally normal.
Notice that the things are called, by many, “air cleaners”.
I’m disputing that air cleaners have no effect on health ( put a box-fan with a 20"-square furnace-filter on the suction-side of it, and it’ll reduce the amount of dust, without any expensive products, and in some areas, in industrial or desert zones, e.g. it’ll likely reduce the harm done to one’s lungs by that air ), and pointing-out that different definitions of “air cleaner” are valid, though not about the same thing.
So why don’t they work?
Even a cheap HEPA filter is good enough to filter COVID.
But, all contaminated air has to actually go through the filter.
This means you need to do several full air exchanges in the required space per hour really if you want to keep people from getting sick. Like a laboratory clean room would do.
And setting up that level of HEPA filtration, is fucking expensive.
I built a very small flowhood for mycology. The filter was $200. The fan another $80. And I’m only keeping a one x two space clean. I imagine it’s just not economical to really apply this technology to schools etc at this point in time.
This paper points out the filtration of SARS-CoV-2 isn’t clear cut whatsoever. Papers stating it could be filtered from the air all demonstrated to have publication bias. The thing about viruses is they are super tiny. On average, a virus is 10x smaller than a bacterial cell. This makes filtration much more difficult to accomplish.
The study found the most effective methods for air purification were germicidal lights, ionisers, and electrostatic cleaners. With HEPA specifically, the filters can snag objects as small as 0.3μm. However, the largest viruses are 500nm or 0.5μm in diameter. Based on the numbers, HEPA filtration is capable of removing the largest viruses from the air, but that’s a small minority of all viruses. SARS-CoV-2 comes in somewhere between 60nm/0.06μm to 140nm/0.14μm in diameter, meaning HEPA filtration can not remove it from the air.
Ahhh… I checked the size but thought microns and nanometers were interchangeable terms. Thanks for the correction.
I was taught μm stands for micrometers, which are 1,000 times smaller than millimeters. Nanometers(nm) are 1,000 times smaller than micrometers(μm), which means nanometers are CRAZY small!
That’s what I was wondering. Like not that it can’t work but that it wasn’t implemented at the sufficient scale to do what it is purported to do.
Even clean rooms don’t stay clean because great apes are not clean, and they have to work in the space. So even the best spaces aren’t fool proof which is why lab teks wear masks and other equipment.
But yeah, work well enough to keep kids etc from being sick, would require lab level air filtration to make a difference. And we’d probably still have to dress the kids up like lab nerds even with lab level filters and fans.
At a guess, it doesn’t matter how clean the air coming out of the HVAC system is if you’re sitting near or talking with someone who’s sick.
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