5 ms·

> "...SARS-CoV-2 is airborne stable in aerosol form for over 3 hours..." see, this is the kind of insinuation that does none of us any good. it's like doing PC

> "...SARS-CoV-2 is airborne stable in aerosol form for over 3 hours..." see, this is the kind of insinuation that does none of us any good. it's like doing PCR to connote live virus particles live for 17 days on surfaces (spoiler: they don't). with that said, i'm down for air purifiers in living spaces† for a whole host of good health reasons, but most commercial spaces and public buildings (like schools) already have HVAC systems incorporating HEPA filters (as good or better than N95 masks). whether the operators change the filters on an appropriate schedule is a different matter however. residential HVAC systems, at least in newer construction, also tend to have HEPA filters (but not always). † i have a blue pure 211+ for my apartment: https://www.blueair.com/us/air-purifiers/blue-pure-211-plus/1695.html https://www.blueair.com/us/air-purifiers/blue-pure-211-plus/...

coryrc 6y ago
If you are in the USA, I don't believe your claim that most commercial or schools have HEPA in their air filtration system, and know it isn't true for new residential in the PNW. The school I attended as a child didn't have any filtration at all, for example.
- clairity 6y ago
  there's certainly variation, regional, by quality level, as well as generational. class A commercial will almost certainly have filtered hvac, for example. my 1930's vintage high school most certainly didn't.
  - coryrc 6y ago
    Filtered, yes, but not HEPA.
fpgaminer 6y ago
> most commercial spaces and public buildings (like schools) already have HVAC systems incorporating HEPA filters (as good or better than N95 masks). So, here's some anecdata. I have a PM2.5 sensor; not a great one, but good enough to measure relative changes. After buying an air purifier the PM2.5 count in our house dropped dramatically and consistently. Whereas the lower end before was a "2", now it reaches to "0"; I'd never seen the sensor register 0 before this. And the spikes from cooking are quickly scrubbed, whereas before they would cause a lingering increase in PM2.5 for the rest of the night. Even though I spend extra to get the higher grade filters for our HVAC, an air purifier still seems to have objectively improved the air quality far beyond what our HVAC was doing. In other words, I'm not sure an HVAC is a good replacement.
- mensetmanusman 6y ago
  This, it is amazing how long small particles linger. It’s like looking in a sun beam and seeing floating fibers near the couch. A very fun experiment to show children is to use a green laser pointer near a carpet floor so it is floating across the floor a couple inches. Then have the children hit the carpet around the beam and the beam will suddenly appear as the light scatters from the micron-sized dust particles. You can see how long it takes them to resettle, and point the laser anywhere to count a crude interaction/second with the light beam to get a sense of how dirty the air is (laser light volume is quite small :))
- clairity 6y ago
  that could be, but i'd note that a 2->0 PM2.5 count drop is likely not material to health as opposed to, say, a 20->2 drop. and furthermore, the time-averaged PM2.5 count while home is more relevant than the minimum absolute value.

coryrc 6y ago

If you are in the USA, I don't believe your claim that most commercial or schools have HEPA in their air filtration system, and know it isn't true for new residential in the PNW. The school I attended as a child didn't have any filtration at all, for example.

clairity 6y ago
there's certainly variation, regional, by quality level, as well as generational. class A commercial will almost certainly have filtered hvac, for example. my 1930's vintage high school most certainly didn't.
- coryrc 6y ago
  Filtered, yes, but not HEPA.

fpgaminer 6y ago

> most commercial spaces and public buildings (like schools) already have HVAC systems incorporating HEPA filters (as good or better than N95 masks). So, here's some anecdata. I have a PM2.5 sensor; not a great one, but good enough to measure relative changes. After buying an air purifier the PM2.5 count in our house dropped dramatically and consistently. Whereas the lower end before was a "2", now it reaches to "0"; I'd never seen the sensor register 0 before this. And the spikes from cooking are quickly scrubbed, whereas before they would cause a lingering increase in PM2.5 for the rest of the night. Even though I spend extra to get the higher grade filters for our HVAC, an air purifier still seems to have objectively improved the air quality far beyond what our HVAC was doing. In other words, I'm not sure an HVAC is a good replacement.

mensetmanusman 6y ago
This, it is amazing how long small particles linger. It’s like looking in a sun beam and seeing floating fibers near the couch. A very fun experiment to show children is to use a green laser pointer near a carpet floor so it is floating across the floor a couple inches. Then have the children hit the carpet around the beam and the beam will suddenly appear as the light scatters from the micron-sized dust particles. You can see how long it takes them to resettle, and point the laser anywhere to count a crude interaction/second with the light beam to get a sense of how dirty the air is (laser light volume is quite small :))
clairity 6y ago
that could be, but i'd note that a 2->0 PM2.5 count drop is likely not material to health as opposed to, say, a 20->2 drop. and furthermore, the time-averaged PM2.5 count while home is more relevant than the minimum absolute value.