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.
Studies have pointed to increased asthma and other respiratory ailments from gas stoves. There's no possible way electric stoves can be anywhere near as bad as literally burning fossil fuels inside your house.
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?
Did you mean induction? Convection just means "An oven with an internal fan to circulate hot air" (so actually not convection in the sense of a temperature difference driven air current).
Induction is using oscillating magnetic fields to heat a ferromagnetic cooking vessel.
> It is Co2 and No2 and vocs that surprise me about the gas stove.
Those are always the byproduct of low temperature open combustion of hydrocarbons, which is what a gas stove is doing.
> 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?
I have an induction stove in a house whose baseline PM2.5, CO2, VOCs are very low (by design). I monitor PM2.5, C02 and VOCs during cooking, and the food itself definitely produces PM2.5, since that's the only measure that increases very much when I'm cooking (and only if I forget to turn on the stove extractor fan).
However, studies have shown that cooking on gas emits many times the amount of PM2.5 as electric. The difference is mostly in the energy delivery method, not the food cooked.
> In your experience is cooking on induction still the #1 poor air quality cause in your house?
Yes, but there isn't much competition anymore now that I've removed all combustion appliances, so only in the comparative sense. Nowadays the biggest air quality issues come from outdoors (pollen, smoke, NOx from nearby freeway).
I have three air monitors I got used. It's a really niche market so I get them cheap. I have a uhoo, laseregg, and airthings. None of them are super accurate and I bet I am measure a lot more than I want but I can see trends enough to make some good guesses.
Can you give some reqs on what your monitoring system looks like?
I've been wanting to monitor our house's air quality for a while, but usually get put off looking at how poorly most affordable air quality monitors are reviewed.
Also, what metrics are most important? There's monitoring out there for pm2.5, pm10, HCHO, CO2, AQI, TVOC, etc, it's a bit of an alphabet soup.
Life is better if you can dust and vacuum on days when you can open the windows. I don't think people understand how much dust the vacuum cleaner doesn't pick up, not because it goes through the filter, but because it gets kicked up by the brush and never enters the fan at all. If you don't believe me, try vacuuming a particularly dirty carpet while barefoot.
Exchanging the air before the dust settles out is a lot better than having to dust a second time.
We've forgotten the unreasonable power of soap in our rush to Better Living Through Chemistry. Someone did tests and showed that a lot of 'cleaned' countertops are gross because the bacteria just get smeared around and homogenized, and counterintuitively the kitchen of a college student may be safer than the kitchen of a 40-something.
When I really clean my counters (parental visits, or realizing entropy is winning), I avoid a lot of cleaning products by first using one of those pot scrapers, then a little liquid soap, a scrub brush, and water. Once I've mopped that up the counter is probably clean, but if I use a cleaning product, this is when I do it. Just enough to swipe over everything, not to lift food particles or dried drops of tomato sauce from last night's spaghetti.
The other forgotten hero is white vinegar. They've tested removing pathogens, heavy metals and car exhaust from garden vegetables (turns out soil contamination is a surface exposure issue more than an absorption issue, even for lead) and white vinegar tested equal to or better than the best vegetable washes - which is to say that none are perfect but some are downright lousy.
Also make sure your sponges aren't gross. Using a gross sponge to clean things makes everything gross. Dipping them in white vinegar and some kettle water is a good way to clean a slightly funky sponge (and burn your fingers - patience is a virtue). Store your sponges elevated, or as I do in one case, prop it up against the wall so one edge (edge not side) is touching the wall and one touching the ground. And don't get sunk cost fallacy with your sponges. Buy in bulk, and when in doubt, throw it out. There's a kind of sponge that comes compressed, a dozen to a pack, and it expands the first time you get it wet. You can throw the spares in your junk drawer and they will get lost.
With plentiful, clean sponges, I tend to use a damp sponge when entropy is winning on the dust front (when it's so dusty you can see the dust from halfway across the room) because otherwise most of that is just going into the air and landing again. A wrung out sponge works wonders, and with a light enough touch I can even use it on books and banker's boxes without leaving any water damage. I recommend practicing on boxes, because if you squeeze the sponge, you might get a water spot. Cleaning dusty bookshelves has gone from an ordeal to just another chore because of this.
What's the evidence that bacteria smeared around on an otherwise visibly "clean" kitchen counter, or dust kicked up from your carpet (which is largely human skin cells anyway) is actually harmful or "unsafe"?
A relative of mine is a 70 year old widower. He's a huge slob and after his wife died 10 years ago, he really doesn't bother to ever clean his house or his kitchen. It's not depression, he's just never been a particularly neat or clean person and simply doesn't care beyond an extremely minimal level. He is in great health and never gets sick, whether from food poisoning or anything else.
Sorry, that's my fault. I said 'bacteria' but the studies were on food-borne pathogens on surfaces. So spreading, for instance, a little e-coli from the pork chop you cooked properly, killing everything, to the asparagus you steamed by touching the same surfaces after 'cleaning' them and not accomplishing your goal.
If you want to clean your kitchen countertop for food safety reason, you will never beat bleach. It’s cheap. It dries forming salt and water. It kills bacteria.
If you need an acidic product because you want to get ride of water stains, I have personally switched from white vinegar to citric acid. It’s cheap when bought in bulk as a powder. You can dilute it to the strength you want to. It takes less space to store and it doesn’t smell.
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.
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.
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.
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.
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.
> 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.
The older I get, the more doctors I see, the less each doctor individually does, the more evident that the rapacious copay of my job-provided health insurance will drive me to less health care, perhaps obviating the need for any health care at all, though my executor will be left holding the bag of paying off outstanding bills.
From what I understood of the article, disinfectant might not do much, because it's dead bacteria which are releasing these toxins as their cell walls rupture. Unless it's a disinfectant which turns these toxins into something less dangerous, lysol won't do much.
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.
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.
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.
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.
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
It’s not that simple though, the study states that replacing the filters removes large endotoxins, but not small ones. The small ones are still present
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.
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.
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?
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?
“ 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]”
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.