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Indoor air filtration could lead to increased airborne endotoxin levels (2020)

• tikkun 4y ago
  Would someone who understands this better mind explaining? For example, should we be stop using air purifiers.
  • SnowHill9902 4y ago
    It’s a pick your poison conclusion.
  • QuercusMax 4y ago
    It sounds like they're saying that you need to replace your filters periodically.
    • dylan604 4y ago
      Isn't this something of a "duh" kind of result though. The packaging on filters give suggested replace after X days kind of info. Yes, the average person doesn't change filters frequently enough, but people with allergies probably do it more regularly. These types of studies just help explain why the manufacture of the filters suggest estimated time of replacing. I say suggest because the filters I use suggest 90 days, but I live with a cat and no carpet, so it gets clogged much faster than 90 days.
  • degovial 4y ago
    • neuroma 4y ago
      More nuance could be: Forcing air through micro particles suspended in a filter creates other kinds of micro particles rarely foujd in air, and with unknown effects on health.
  • thaeli 4y ago
    For particulates, media filters actually get more efficient as they get dirtier. They also get harder to blow air through, which means less air volume with normal fans or higher energy consumption with VFD fans. I'm simplifying a bit, but traditionally change intervals are based solely on keeping air resistance within acceptable values. This paper presents a different mechanism by which IAQ can be negatively impacted by a dirty media filter. It's possible that this affects change intervals or other measures, and it's possible that this is a matter of theoretical concern but in practice doesn't matter much. It's cliche to say that a study's conclusion is that there should be more studies, but that's really the case here.
  • doctoboggan 4y ago
    If you have a dirty filter it may be actually making your air quality worse (in some ways) than just not running the filter at all. It seems like bacteria caught in the filter are dying and releasing endotoxins, which are small enough to escape the filter and then are sent throughout the environment.
    • the_only_law 4y ago
      > If you have a dirty filter it may be actually making your air quality worse (in some ways) than just not running the filter at all. I might have to check the air filter. I’ve been having the worst sinus issues I’ve ever had outside a sinus infection. My eyes constantly tear up, my nose will on occasionally completely shuts, and I’ve been having back to back sneezing attacks. I originally chalked it up to seasonal allergies, as pollen count is quite high, but I’ve been suspicious of indoor air quality as well. To add to the confusion I got COVID around the same time it started.
      • beebmam 4y ago
        It might be a good idea to seek medical advice from your doctor
        • the_only_law 4y ago
          Last time I spoke with a doctor about sinus issues they just told me to grab some OTC remedy and that was mostly it
          • specialist 4y ago
            Someone, somewhere has the answers you need. I try tell everyone to not accept "no" or "i don't know" for answers if they're still suffering. FWIW, eventually had sinus surgery, now do saline rinse every day, astelin antihistame spray changed my life. YMMV. Good luck.
          • olyjohn 4y ago
            The more doctors I see, the more I just feel like a ticket in a queue that needs to be closed out and billed ASAP.
• ryanmarsh 4y ago
  The contrast indicates that regularly replacing the HEPA filters of APs could represent an effective method of avoiding increased endotoxins in the filtered air. That's a pretty clickbaity paper title. The lede was buried. A better title would have been: Regularly replacing HEPA filters may reduce endotoxins in filtered air I'm a high school drop out so what do I know.
  • enragedcacti 4y ago
    From my understanding the filtration process itself (through a dirty filter) is creating the endotoxins that wouldn't have otherwise been present (although other pm2.5 particles would be of course). e.g. A car with a catalytic converter avoids increases of certain gases in the air, but it doesn't reduce what is already present. In that light both the title and the suggested mitigation seem pretty straightforward.
    • kkfx 4y ago
      The point is probably about concentration: if certain "pathogens" (no matter their nature, it's valid from all bacteria, viruses, poisonous chemicals etc) are present but below a certain concentration they are effectively harmless. If more concentrated they might be harmful. Under certain condition a local concentration might form a colony that act as a persistent source of potentially harmful "pathogens". A bit more complex, but a good generic description. What it's not clear to me is the definition of "purifier" and they operating principle: VMCs are normally harmless because they do not blow humid air and they keep air flowing so it's hard to offer room for "colonization" in most cases. That's the same principle we have for modern water heaters, classic ones, large pressurized balloons filled of hot sanitary water do require a regular daily extra-heat-up against legionella, modern ones with a not pressurized hot-water balloons and just a spiral pipe inside to "instantaneously" heat the sanitary water flowing in the pipe in most country do not demand anti-legionella heating cycle because they do not offer room for it's development. So much of the point of this study should be define the kind/family of devices they have testes.
  • bombcar 4y ago
    "Dirty filters can release bacteria poop" wouldn't get as much interest.
• 5e92cb50239222b 4y ago
  Roughly speaking, 2× the levels compared to purifier off, if I understand the paper correctly. Considering that running a purifier lowers my yearly average PM2.5 exposure by approximately 60-80×, I think I'll continue running the purifier. Interesting data nonetheless.
  • outworlder 4y ago
    Apparently, all you have to do is replace the filter, which should be done anyways. EDIT: and apparently I was wrong. "Overall, endotoxins deposition in the alveolar region increased regardless of whether the air purifier was loaded with used or new HEPA filters."
• kjax 4y ago
  Can someone with access to the article comment on the researchers' findings for how long new HEPA filters typically last, before they start emitting nontrivial quantities of endotoxins?
  • oao 4y ago
    The article seems to be available to everyone at https://sci-hub.st/10.1016/j.envint.2020.105878 https://sci-hub.st/10.1016/j.envint.2020.105878
• m0llusk 4y ago
  It seems like filters designed for regular cleaning could address this.
  • deleted 4y ago
    [deleted]
  • hollerith 4y ago
    All the filters I know of for the kind of particles most deleterious to health (i.e., small enough to get deep into the lungs) cannot be cleaned. Do you know of a type that can?
  • outworlder 4y ago
    Generally speaking, HEPA filters can't be cleaned.
• sudden_dystopia 4y ago
  Re endotoxins from Wikipedia: “ Inflammation induced by LPS can induce cellular senescence, as has been shown for the lung epithelial cells and microglial cells (the latter leading to neurodegeneration).[55]”
• thecrims0nchin 4y ago
  I have been monitoring my indoor house air for two years now, and attempting to keep my air as healthy as possible. I have found that: 1) If you are lucky enough to live in an area with clean air, opening a window is orders of magnitude quicker and more effective way to clean air. 2) Gas stoves are the worst thing you can do to your house air (a fume Hood can partially mitigate this) 3) You should be weary of using any cleaning product without ventilation (open windows for a whole day) 4) HEPA filters work, but slowly. Realize you can sneeze into these things and some % of your sneeze goes right through/around the filter. They need multiple passes to fully clean the air. Big quiet HEPA filters are the way to go. 5) Activated Carbon filters grab the stuff HEPA can't but they are very slow at it, and I haven't found anything commercial that works. The thin black layer on filters doesn't work, you need something more commercial like the ones people use when they are home growing weed. IMO, the effect of these is really hard to measure and I wouldn't personally suggest this right now. 6) Humidity control is important for health and has a relationship to air particulates All of this work and basically I open windows any nice days, when I'm cleaning, and when I cook. Many HEPA filters and a beefy carbon filter cant compete with this. Even if it means running up the heat/AC bill a bit. I'm considering some sort of heat exchanger with filters in the future, but that is overkill. I am privileged to have nice air outside though and I realize this isn't THE solution for everyone. As far as this article goes. HEPA filters are supposed to be replaced every 6 months, but even older filters get rid of so many particulates that we KNOW are bad for you it seems worth this tradeoff. Maybe a HEPA filter with a UV light could help (not by much probably), but be weary of "24 stage filters" and all that nonsense. HEPA is all most houses really need.
  • hgomersall 4y ago
    Have you compared gas stoves to electric stoves? With our induction hob we found cooking in general produces loads of pm10.
    • thecrims0nchin 4y ago
      That's really interesting! I switched from electric to gas (I regret not doing induction) and I found the pm10 and 2.5 are very similar for both. It is Co2 and No2 and vocs that surprise me about the gas stove. I'm no expert, just a lay person trying to make sense of it all but maybe the PM is from the food and therefore pretty consistent for all types of cooking?
• zcw100 4y ago
  Wait, so bateria that are in your home are getting sucked into the filter like they're supposed to do, die and release endotoxins. But they're going to die anyway and still release those endotoxins but it's just going to be all over my couch that I sit on every day. Ok, maybe that nasty filter you haven't changed in a year provided an environment for the bacteria to grow and the fan disperses it. Sure, I get it if it's some nasty filter you haven't changed in over a year. That's why you don't wait a year to change them. That's like saying, "Bathrooms may provide a breeding ground for mould and bacteria making your home less hygienic!." Ya, no kidding. That's why you clean your bathroom.
  • thecrims0nchin 4y ago
    I guess the difference is whether the bacteria die and produce endotoxins on your HEPA filter which is circulating air though your house, or if the bacteria die in your carpet or on your countertop where it is more likely to be cleaned in the next 6 months and less likely to be recirculated as breathing air. Regardless, I agree with you. If the filter prevents you from breathing X% bacteria and y% of bacteria produce endotoxins then your choices are -Breathe in that extra x% bacteria and have them produce xy endotoxins directly in your lungs -Kill the bacteria but breather in their xy endotoxins that are dispersed in the air. Seems like a zero sum game when
• Wistar 4y ago
  I built a couple purifiers using a box fan atop a cube made of four HEPA (MERV 13) 20x20x2 furnace filters. Inside the cube, I hung two UVC lamps, one merc vapor at 254nm and one LED-type at "far uvc" 222nm, in the hopes it would kill some of the bad things but question whether the air in the chamber is there long enough for a good kill. None of us in my household has contracted Covid but that may just be luck.
• nanomonkey 4y ago
  Endotoxins, mostly Lipopolysaccharide released by bacteria as they die, appear to be broken down by UV treatment. So including a UV lamp after your air filtration system may mitigate this. Another option would be to use water to filter your air, like a giant bong, allowing you to dispose of the water as it gets dirty. Lastly endotoxins can be baked out at 250-300 deg C, so a carbon filtration system could be periodically baked out to be reused. I doubt any plastic fiber hepa filter could withstand such temperatures.