I support more research but anecdotally HEPA air filters changed my life. I used to get pretty bad respiratory infections every winter but after getting these that went away. I’m talking the simple kind with basic charcoal prefilter and fiber HEPA filter which are about $150 at most home stores or big box stores. Never used any ionization or ozone. The interesting bit is the newer ones even measure air particulates and have a variable speed option where they will speed up when they detect high pollution… Which turns out is mostly from me cooking.
HocusLocus · 1h ago
Breathing and sleeping in negative ionized air for 40 years. Just high voltage potential -7 to -10kVDC and spread carbon hairs (better than metal spikes) to launch it.
Walls and floors always have positive charge conducted from the ground outside relative to the air, no sparks means ozone in too small concentrations to worry about. Dust, smoke, bacteria and viruses stick to walls not the inside of lungs and the air is clean and odorless. You can shine a very bright flashlight through it in a dark room and see absolutely no beam. Every so often you sponge off the walls with strong cleaning solution. Latex paint stains easily near the device which is a subtle way of reminding you how germy it really would have been. Use plastic over walls near the device to save yourself some color matching and painting.
Over all these years, the most annoying thing has been other people trying to sell me HEPA filter solutions with screaming fans that need accessory replacement often. They insist I'm killing myself with ozone as a fear tactic. Few people sell just ionizers or sabotage the concept by selling weak/ineffective ones... because HEPA is big money.
Ionizers use tiny energy and no recurring supplies. Just make sure your electronics are grounded well.
0b110907 · 19m ago
Do you have a more detailed writeup about how you've set this up?
jld · 1h ago
Double blind studies are helpful when we do not understand they underlying dynamics of a complicated system (like a body) but we want to learn what effect a change has on that system (like a medicine).
If we know pathogens cause disease, and we know filtering removes pathogens from the air (and we can test and verify that) we don't need to run a double blind study to verify they work.
It's the same reason you don't need to run a double blind study on whether seat belts work. We understand the cause and effect of car ejections and windshield/steering wheel impacts on human bodies. Seat belts are designed to mitigate these incidents and are tested and validated in the lab using formal science and engineering.
closeparen · 26m ago
You're not going to spend 100% of your day in the coverage of one of these things, so what's the dose response? How many hours per day of filtered air equals how many fewer infections per year? Does air filtration in your workplace matter at all if you have young kids in school? Does air filtration in a school matter at all if the kids are all together on a poorly ventilated bus for two hours a day?
Seems like some evidence would be helpful.
valbaca · 54m ago
> It's the same reason you don't need to run a double blind study on whether seat belts work.
We might need some historical investigation into the road that was travelled to get seatbelts to where they are now (physically, legally, and socially). I'm a millennial and I remember growing up where similar arguments were made:
- "If it's my time to go, then it's God's will"
- "It's uncomfortable"
- zero/inconsistent law enforcement
- "If the car rolls over than it can trap you"
To now, where it's entirely automatic and incredibly wild to even suggest being without a seatbelt.
throw0101c · 18m ago
In 2023 there was a conference about Chemistry of Indoor Environments (CIE) that looked at the research that was done over a ten-year period; opening presentation:
Generally: avoid any use of electronics to 'do stuff' to the air or pathogens (e.g. UV) and just use high-MERV / HEPA filters, and use an ERV to vent stale air and bring in (filtered, conditioned) outside air.
rogerkirkness · 5m ago
Yeah the whole 'just use HEPA' has been what's worked for us after about a half dozen different air purifiers of experimentation. I noticed the positive ionization things changed my heart rate variability which was spooky.
monster_truck · 2h ago
Who in the world is installing UV in forced air systems without running an activated carbon filter to remove ozone? The guides I followed when I installed mine called this out multiple times.
No comments yet
nextcept · 1h ago
All the tech in the world won't change anything if people don't focus on airflow and airchanges. Air needs to move and be replenished with air from the outside. Filters/UV/etc are just a bonus.
throw0101c · 11m ago
> * Air needs to move and be replenished with air from the outside. Filters/UV/etc are just a bonus.*
Outside air needs to be filtered otherwise you can bring in pollen and other things (e.g., exhaust/brake dust from cars if near heavy arteries). Avoid UV for residences:
Or for anyone on the west coast the last 5 years, nasty smoke.
jerlam · 9m ago
Yes, there is a whole certification system for measuring how well an air purifier works (CADR - Clean Air Delivery Rate) but consumers are easily distracted and confused by flashy features that promise everything but usually don't do much.
ortusdux · 1h ago
I've been running an airgradient sensor for a year now and as a result I am seriously considering adding a MERV to my HVAC system. Ideally I'd like to get two more sensors (one outside, one in the HVAC ducts) and setup home assistant to govern air exchanges.
quickthrowman · 1h ago
If by ‘people’ you mean ‘mechanical engineers’, they already do, see ASHRAE 62.1 - Ventilation and Acceptable Indoor Air Quality
this is similar to anti-vax propoganda - setting an ever higher bar and saying we need that first there is no particular reason to think lab tests are not most of what we need.
DANmode · 2h ago
UV-C / hydroxyl generators or bust
searine · 1h ago
Funded by National Institute for Occupational Safety and Health at the Centers for Disease Control and Prevention aka NIOSH / CDC
jerlam · 4m ago
Which has been completely gutted by the current administration.
ungreased0675 · 1h ago
Fair argument, but let’s not forget that indoor air quality, HEPA filters, and upper air UV systems weren’t even allowed to be discussed as solutions to airborne transmission of viruses not that long ago. It was all about masks/no masks, remember? It’s a little unfair to say that things haven’t been studied, when it would have been career damaging to do so until very recently.
dgacmu · 44m ago
This is baloney? Air quality experts like Richard Corsi (UC Davis, now, poor guy, the dean of the college of engineering) have been advocating for increasing both external ACH (air changes/hour) and filtration ACH since nearly the beginning of the pandemic.
> Early in the pandemic, his efforts focused on lowering inhalation dose of virus-laden aerosol particles indoors. He led an effort to develop an educational tool for assessing parallel interventions for lowering inhalation dose for aerosols and risk of infection in buildings. His concept of a low-cost and effective do-it-yourself air cleaner to combat virus-laden aerosol particles and wildfire smoke has become known worldwide as the Corsi-Rosenthal Box. He recently chaired a National Academies committee responsible for the 2024 report, “Health Risks of Indoor Exposure to Fine Particulate Matter and Practical Mitigation Solutions.”
An awful lot of people who pay attention to engineering solutions for airborne risk reduction - the people who know what ASHRAE is - were saying exactly the same thing throughout nearly the entirety of the pandemic. Because of their advocacy and data, as one example, we got HEPA filters installed in our kids' elementary and preschools as part of the strategy to resume in-person education.
craftkiller · 58m ago
Got a source? I don't remember anyone objecting to studying HEPA filters' impact on airborne viruses. In fact, I've found studies on that exact topic from that time period. The CDC was saying that HEPA combined with masks was more effective than masking alone back in 2021 (but masking alone was better than HEPA alone)
> Without the HEPA air cleaners, universal masking reduced the combined mean aerosol concentration by 72%. The combination of the two HEPA air cleaners and universal masking reduced overall exposure by up to 90%. The HEPA air cleaners were most effective when they were close to the aerosol source
Karolinska Institute in Sweden did a study during the pandemic that had findings of virus particles in every location in the hospital ventilation system, past all filters and air purifying. It was a early finding that indicated the role of recycled air in spreading the virus in places like airports, planes, trains and large buildings like shopping malls. The covid virus is so small and so effective as a airborne virus that even hospital filters had a limited effect.
valbaca · 59m ago
> It was all about masks/no masks, remember?
You're clearly pushing an agenda. The problem is that these kind of filtration systems couldn't be rolled out en-masse across the world.
During COVID hospitals absolutely were using air filtration systems and places where it made sense (I remember COVID doctor's conferences had advanced filters for each room).
jeffbee · 1h ago
No, I do not remember that. I'm pretty sure you just made it up. Air filtering is obviously long-studied, and if you are alluding to COVID-era events I seem to recall that one of the first large-scale responses that happened in my region was the subway operator installed up-rated HEPA+UV air cleaners on every car.
If you want to sustain this claim, show us the process by which someone's career was truncated by researching air filtration.
Walls and floors always have positive charge conducted from the ground outside relative to the air, no sparks means ozone in too small concentrations to worry about. Dust, smoke, bacteria and viruses stick to walls not the inside of lungs and the air is clean and odorless. You can shine a very bright flashlight through it in a dark room and see absolutely no beam. Every so often you sponge off the walls with strong cleaning solution. Latex paint stains easily near the device which is a subtle way of reminding you how germy it really would have been. Use plastic over walls near the device to save yourself some color matching and painting.
Over all these years, the most annoying thing has been other people trying to sell me HEPA filter solutions with screaming fans that need accessory replacement often. They insist I'm killing myself with ozone as a fear tactic. Few people sell just ionizers or sabotage the concept by selling weak/ineffective ones... because HEPA is big money.
Ionizers use tiny energy and no recurring supplies. Just make sure your electronics are grounded well.
If we know pathogens cause disease, and we know filtering removes pathogens from the air (and we can test and verify that) we don't need to run a double blind study to verify they work.
It's the same reason you don't need to run a double blind study on whether seat belts work. We understand the cause and effect of car ejections and windshield/steering wheel impacts on human bodies. Seat belts are designed to mitigate these incidents and are tested and validated in the lab using formal science and engineering.
Seems like some evidence would be helpful.
We might need some historical investigation into the road that was travelled to get seatbelts to where they are now (physically, legally, and socially). I'm a millennial and I remember growing up where similar arguments were made:
- "If it's my time to go, then it's God's will"
- "It's uncomfortable"
- zero/inconsistent law enforcement
- "If the car rolls over than it can trap you"
To now, where it's entirely automatic and incredibly wild to even suggest being without a seatbelt.
* https://www.youtube.com/watch?v=vt0GLbi20Q4
* https://indoorchem.org/publications/
Playlist of the various presentations from the conference:
* https://www.youtube.com/watch?v=J2iHOCI2hz4&list=PLsc2-5fAgM...
Generally: avoid any use of electronics to 'do stuff' to the air or pathogens (e.g. UV) and just use high-MERV / HEPA filters, and use an ERV to vent stale air and bring in (filtered, conditioned) outside air.
No comments yet
Outside air needs to be filtered otherwise you can bring in pollen and other things (e.g., exhaust/brake dust from cars if near heavy arteries). Avoid UV for residences:
* https://www.youtube.com/watch?v=xLwHmfdwO9s
https://static1.squarespace.com/static/6320b844c3820725e4d56...
> Early in the pandemic, his efforts focused on lowering inhalation dose of virus-laden aerosol particles indoors. He led an effort to develop an educational tool for assessing parallel interventions for lowering inhalation dose for aerosols and risk of infection in buildings. His concept of a low-cost and effective do-it-yourself air cleaner to combat virus-laden aerosol particles and wildfire smoke has become known worldwide as the Corsi-Rosenthal Box. He recently chaired a National Academies committee responsible for the 2024 report, “Health Risks of Indoor Exposure to Fine Particulate Matter and Practical Mitigation Solutions.”
An awful lot of people who pay attention to engineering solutions for airborne risk reduction - the people who know what ASHRAE is - were saying exactly the same thing throughout nearly the entirety of the pandemic. Because of their advocacy and data, as one example, we got HEPA filters installed in our kids' elementary and preschools as part of the strategy to resume in-person education.
> Without the HEPA air cleaners, universal masking reduced the combined mean aerosol concentration by 72%. The combination of the two HEPA air cleaners and universal masking reduced overall exposure by up to 90%. The HEPA air cleaners were most effective when they were close to the aerosol source
You're clearly pushing an agenda. The problem is that these kind of filtration systems couldn't be rolled out en-masse across the world.
During COVID hospitals absolutely were using air filtration systems and places where it made sense (I remember COVID doctor's conferences had advanced filters for each room).
If you want to sustain this claim, show us the process by which someone's career was truncated by researching air filtration.