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[quote=Anonymous][quote=Anonymous][quote=Anonymous][quote=Anonymous]APS did not buy HEPA filters. They should have but did not. They bought some other weird technology. [/quote]

I was told that each room has a hepa filter air purifier. I thought UV was better[/quote]

Lots of misinfo in this thread.

The company held itself out as providing "hepa-grade" filtration based on its own testing, but it isn't a true HEPA filter. There's no UV element. The filters do have an ionizer element.

UV is harmless, theoretically could work to sterilize the air without having to filter down to .1 micron like HEPA does. Independent testing is mixed.

Ionizing filters don't deliberately pump ions into the air, they have an element that ionizes some molecules as they enter so they stick to the (non-HEPA-grade) filter better. Problem is a floating oxygen ion will join with O2 to make O3, aka ozone, which is a lung irritant. Independent testing of older models tended to show that some of these devices could cause ozone levels to exceed recommended limits, but only if used in small, unventilated areas. More recently they haven't even been able to show that in testing, though the theoretical possibility remains. The technology still doesn't work as well as HEPA though.

HEPAs are expensive, loud, less energy efficient, and require more maintenance, because all they do is try to force a lot of air through very small holes. That's why businesses keep being drawn to these other technologies, even though their track record is mixed and they don't necessarily work as well.

NYPS had a similar issue with buying less-than-ideal filters: https://ny.chalkbeat.org/2021/8/18/22630636/air-purifiers-hepa-nyc-schools-covid . It seems like HEPAs would have been better, the non-HEPA ones still help, and combined with other mitigation measures will probably be good enough. [/quote]

Great explanation.  Thank you.[/quote]

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