9 ms·

After getting a (non-DIY because as much as I like hobby electronics I have a tendency to scope creep my little projects straight into incompletion) about a yea

After getting a (non-DIY because as much as I like hobby electronics I have a tendency to scope creep my little projects straight into incompletion) about a year ago, my main learnings have been: - Cooking is insanely bad for the air in your house, even with an outside-venting hood. Any sort of medium-high heat cooking will spike the PM2.5 to multiple times that of the haziest days here in NYC, and with the windows shut it will stay elevated for hours after. - The 20" box fan + MERV furnace filter hack is super effective for cutting down on the PM. A few days this July the wildfire smoke from the west coast settled on NYC and we had 40-70 ug/m3 PM2.5 outside. The box fan filter took it down to around 5 in a matter of minutes. I didn't even bother taping the filter to the fan. - My A/C system's ability to precisely hold the temperature within fractions of a degree of the thermostat setting is impressive. - With two people working from home in an old, unventilated-but-kinda-drafty ~700 square foot apartment, the only thing that gets the CO2 levels into "drowsy" territory (my original point of curiosity when buying the sensor) is running the gas oven for a while.

Someone1234 5y ago
> I didn't even bother taping the filter to the fan. I found bungee cord with J hooks works really well. As you correctly point out, you don't need to secure it at all, but it is annoying to tap the box fan and have the filter fall over.
- lisper 5y ago
  That seems odd to me. I've never tried this, but it seems to me that you have to put the filter on the intake side of the fan, other the fan would just blow it off. And on the intake side, would not the pressure differential hold it in place?
  - wholinator2 5y ago
    I feel like you could place it on either side of the fan as long as air is directed to go through it. My personal intuition is filter then fan but I don't see a reason it couldn't go the other way. I wonder why most devices place it on the intake though. Maybe to prevent dust from getting inside a device, but even then it'd only protect the fan from dust. Hmmm...
    - johntash 5y ago
      Fan and then filter could lead to the fan blades getting dirtier faster. Other than that, I'm not sure if it makes a difference as far as effectiveness.
  - late2part 5y ago
    Good on you, master of the obvious!
rtkaratekid 5y ago
What sensor are you using? Just curious.
- tpmx 5y ago
  For DIY, there was a pretty good discussion on suitable sensors in the AirGradient post from three months ago that Jeff linked to: https://news.ycombinator.com/item?id=27125060 https://news.ycombinator.com/item?id=27125060 tl;dr: seems like you want an NDIR sensor (https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor). Some options, with digikey @1 prices: Senseair S8 (Sweden): $48 Sensirion SCD30 (Switzerland): $63 Amphenol Telaire T6713 (US): $96 If I were to buy an expensive black box iot solution, I'd at least verify that it had an NDIR sensor.
  - s0rce 5y ago
    I'm using an SCD41 with an OLED+microcontroller (using Sensirion's example code hacked a bit) and it seems to work well, cheaper than the NDIR using some photoacoustic magic.
    - tpmx 5y ago
      $37 @1, but not in stock at digikey, and an 11 week lead time. It's pretty tiny... I wonder if/when it will be possible to put a high quality co2 sensor in an IP68 iPhone...
      - s0rce 5y ago
        I had purchased the dev kit sek-scd41 but its out of stock as well. The SCD41 also does RH and T so you don't need a separate sensor for that.
- macNchz 5y ago
  I'm using an Awair Element, I didn't do a ton of research on alternatives, but the app is pretty good and it "just works".
Scene_Cast2 5y ago
I think the draftiness is key. In my findings, in a "modern" house (double-paned windows, built in the last 20 years), sleeping with the door closed will spike CO2 to 4 digits. The other thing is that air really needs to circulate in order to lower CO2 - opening a window in a room will not lower the hallway CO2 unless there's at least some draft / air movement.
- 5e92cb50239222b 5y ago
  Temperature difference helps if there's no wind. In winter time CO₂ drops from 4000+ ppm to ~450 in only a couple of minutes after opening a single window (with inside to outside temperature difference of 50°C or higher). In summer it drops to ~600-700 and stays there, and even this takes hours.
  - y4mi 5y ago
    50°C difference or even higher? Damn mate, even Siberia only gets around -34°C which is less then that of you target the usual 18-21°C. Your winters sound terrifying.
    - theluketowers 5y ago
      Saskatchewan Canada can easily reach -40°C for several weeks during the winter.
      - JamisonM 5y ago
        What? Maybe in the most northern reaches.. even then "for several weeks" is a stretch.. even Uranium City doesn't hit -40°C every winter!
        bbarnett 5y ago
        There is often confusion between wind chill, and actual temps. But the parent is not inaccurate, for they did not mention "each year". Even 10 minutes North of Ottawa, I saw -42C, real, not just windchill, for a week, about a decade ago.
goodpoint 5y ago
> - Cooking is insanely bad for the air in your house Hold on! Not all particulates are equally harmful - and by far! A particulate sensor detects water vapor or particles of (non-burnt) cooking oil that are harmless to humans. In the same way, it detects very dangerous (carcinogenic) compounds from combustion engines or burning coal or wood. Cooking is in no way "insanely bad" (unless you are grilling your food black or cooking on an open wood/coal fire)
- 5e92cb50239222b 5y ago
  It does not measure water vapor, at least not the one I'm using (PMS5003). I always have windows tightly shut because of the extreme pollution outside, so 100% humidity is easy to reach simply by mopping the floors (which stay wet for hours after). It does not change PM measurements one bit. Fry a couple of eggs though, and PM 2.5 quickly goes over 100 µg/m³. Burn a piece of meat just a little bit and see it rise over 300 µg/m³.
  - eutectic 5y ago
    What about suspended water droplets?
- crazygringo 5y ago
  The thing that sends my PM2.5 skyrocketing the most is, interestingly, my toaster oven. Like from 50 to 1500 in the space of 10 min. No food needed within -- just the heating itself. I have no idea what the particles are though -- metal? Paint? Carbon from burnt residue? Or just whatever the heating element itself is made of? Separately, cooking with gas (oven+stove) also sends CO2 way way up -- in my kitchen, from 500 to 1300 or so within 20 minutes. And that's with my range hood on.
  - thrashh 5y ago
    Dust in the toaster?
  - sneak 5y ago
    A lot of range hoods don't actually exhaust outside, and just suck stovetop air over some steel wool to condense the grease particles somewhere other than your walls. Not saying that's the case here, but several times I thought the range fan was exhausting the air, only to learn upon examination that it was just shooting it back out into the same room.
r00fus 5y ago
When the air is good outside, I typically run our whole-house fan pulling in outside air while I'm baking or making dinner - didn't consciously decide on it, but it just seemed to feel better to do those together. Now I really need to investigate more details - like does induction cooking (vs. gas) improve the quality? What about the type of food (ie, cooking vegetarian vs. grilling sausages)?
- beenBoutIT 5y ago
  Investigate fume hoods and implement a good one with enough make-up air to take everything coming off of your range out of your kitchen. Air quality's negatively impacted by heating pots/pans/etc. and their contents up and less about how they're being heated. With the exception of h2o just about everything you cook has a negative impact on the air quality and the pans themselves are doing all sorts of interesting things to the air when they get hot.
  - velosol 5y ago
    I agree on PM2.5 but gas is clearly worse from a CO2 (and other combustion byproducts) point of view compared to induction which is limited to 'just' the food items and the containers they're in.
nsporillo 5y ago
The box fan and high-merv filter hack is a good idea, but proper ventilation of filtered outdoor air is the best solution. Not always practical, but historically buildings breath via air infiltration due to pressure differentials, stack effects, wind, etc - might as well bring in the air on your own terms rather than it leak through your walls and insulation.
- Tenoke 5y ago
  I'm not actually sure it's always the best. My rooms face the street and I can't tell if the air I get on that side is actually better than just having air from the other side +purifier.
  - nsporillo 5y ago
    Quality Energy/Heat Recovery Ventilators (which are basically mandated by code [in some jurisdictions] in modern construction due to air tightness requirements) should allow you to select the filter with the MERV value that works best for your situation. But to be fair, you may have a good point. Vehicle emissions and tire wear generates particulates consider to be ultrafine (0.1 max nanometer), which is even difficult for HEPA filters to deal with.
- macNchz 5y ago
  On my leafy Brooklyn street the particulate pollution outside is well within the recommended levels nearly all the time, so thankfully there's not really a pressing need to retrofit modern ventilation into a 120 year old house. That is, assuming the presence of wildfire smoke from 3000 miles away remains a rare event, which...who knows.
karmelapple 5y ago
Agreed with all these observations, especially gas oven or stove usage! Our former third floor ~1200 sq ft condo would spike CO2 up well over 1400 ppm when we’d run it, and almost instantly. Even just with two people working from home, much of the space would quickly get up to 800 or 900 ppm. I’d usually open windows as I saw it creeping up, which would quickly reduce CO2 to under 600, and then it would slowly creep up over the day.
wintermutestwin 5y ago
>The 20" box fan + MERV furnace filter hack Living here in the west with hyper toxic AQI for the better part of two months now, I decided that the low CFM and leakage of a DIY box fan are not adequate to keep up. I went with a far more industrial solution: I went to an indoor grow shop and bought an activated carbon filter and high CFM inline fan. Cost $150 and is a bit noisy, but has been well worth it.
- fosk 5y ago
  Link?
  - wintermutestwin 5y ago
    I wouldn't recommend this specific setup, but these are the type of filters/fans I am talking about: https://www.amazon.com/VIVOSUN-Inline-Controller-Ducting-Ventilation/dp/B07YZKWNG5/ref=sr_1_7?crid=I4OFRYHOPKQC&dchild=1&keywords=carbon+filter+for+grow+tent&qid=1631143912&sprefix=carbon+filter%2Caps%2C298&sr=8-7 https://www.amazon.com/VIVOSUN-Inline-Controller-Ducting-Ven...
- jonahhorowitz 5y ago
  You can buy carbon activated MERV filters. I got some from Nordic Pure.
- Exuma 5y ago
  what MERV rating is that. I do that now but I thought it's MERV 8 which really won't remove much at all
- rsync 5y ago
  I’m surprised to hear this - a standard box fan from ace has something like ~600 cfm, right ? That’s fairly high - what is the size and cfm of the fan you bought?
  - wintermutestwin 5y ago
    Not when you strap an HVAC filter on it. My setup is ~600cfm with much more filtering. Not sure what the MERV is but the cylindrical layer is much thicker and heavy duty than an HVAC filter.
throwawaysea 5y ago
There are better setups than the 20" box fan + MERV furnace filter. For example check out this similar DIY design that reduces risk of an electrical fire by making it easier for the fan to draw air: https://encycla.com/Corsi-Rosenthal_Cube https://encycla.com/Corsi-Rosenthal_Cube
- rovr138 5y ago
  From that page, >The EPA funded a study by Underwriters Laboratories (UL) which tested box fans with MERV-13 filters attached, finding them to not present a fire hazard even in extreme, modified conditions. Then it links to, https://chemicalinsights.org/wp-content/uploads/DIY-Box-Fan-Report-2021.pdf?utm_source=Chemical+Insights&utm_campaign=d52ba63ea8-July_2021_Newsletter7_13_2021_13_4&utm_medium=email&utm_term=0_09fecf83d2-d52ba63ea8-119531236 https://chemicalinsights.org/wp-content/uploads/DIY-Box-Fan-... which says, >Two-Sided Obstruction >Figure 6 shows the time series of monitored temperatures under extreme condition where both sides of the fans were blocked. Despite the severe blockage of air flow, temperatures of all five box fans peaked within the first 20 minutes and then plateaued, remaining steady for the remaining 7 hours. Winding temperatures had the largest relative increase of 30 to 57 °C above ambient temperature, with peak absolute winding temperatures remaining at or below 80 °C. Peak temperatures on other fan parts did not exceed 50 °C. > Temperatures at the power cord, guard, and switch, remained close to ambient room temperature (±6 °C) during all filter test scenarios as well as during the one-sided blocked tests. For the two-sided blocked tests, temperatures at the power cord, guard, and switch increased initially before plateauing to a steady temperature for the remainder of the 7-hour test duration. All fans remained operational for the 7-hour test duration and did not show any signs of potential hazard or damage.
tootie 5y ago
Not an expert but from what I've read, gas stoves are by far the worst. Electric (including induction) are much healthier.
TrevorJ 5y ago
The gas stove thing was surprising, but of course it makes a ton of sense!
jeffwass 5y ago
If someone knows the answer to this I’d be interested to know : Do different PM2.5 components affect the body differently, even for the same overall count? Eg, are the PM2.5 particulates from burning toast comparable in bodily health impact to a similar PM2.5 count coming from a heavy Diesel engine’s exhaust (which I presume would have a different particulate makeup).
- pirate787 5y ago
  My understanding is that PM2.5 with heavy metals or toxic payloads is more dangerous, but both are dangerous.
- pyk 5y ago
  Still an active field of study but your intuition seems to be right. One study is here [1]. Combustible “types” of PM are usually worse (think smoke / carbon) vs. vaporous types of PM. The method of action is hypothesized to be the carbon particulate getting lodged in your lungs (similar problems from smoking, carbon nanotube inhalation, or charred foods). [1] https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.0800185?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.0800185?url_v...
jozzy-james 5y ago
- Cooking is insanely bad for the air in your house, even with an outside-venting hood. weeps in searing steaks with no hood at all :'(
bfirsh 5y ago
One thing I found is our furnace fan and its filter is surprisingly quick and effective at cleaning up wildfire smoke (and cooking smoke...) https://twitter.com/bfirsh/status/1434677458171678721 https://twitter.com/bfirsh/status/1434677458171678721
graeme 5y ago
> Cooking is insanely bad for the air in your house, even with an outside-venting hood. Any sort of medium-high heat cooking will spike the PM2.5 to multiple times that of the haziest days here in NYC, and with the windows shut it will stay elevated for hours after. I’ve found this varies quite a bit. Though, I don’t do a ton of high heat cooking, so maybe there’s no way to do that without pollution. But at medium to low temperatures, you can get crazy variance in AQI output: * Lack of enough oil/butter in the pan will send levels soaring * Cooking one thing in the pan then another after is very bad. Eg I used to cook sweet potatoes then add meat after and not clean in between to save waiting. Boy was that bad for the air. I think it’s because tiny bits of food you may not even see stick to bottom of pan and burn * Browning is when it gets worse. Any kind of browning on foods spikes pollution. * Any food particle that gets on the burner will invariably lead to hazardous AQI levels. Like even a single fleck of meat left cooking will fill the house. You may not necessarily smell it as much as other things * Turning heat off at end of cooking works wonders. I do this with bacon and it takes it from a hazard to not even spiking aqi. Finished product looks and tastes the same
- faeyanpiraat 5y ago
  "Turning heat off at end of cooking" What is the alternative?
  - Sander_Marechal 5y ago
    I think he means that you turn the heat off before cooking is finished and let the residual heat of the pan do the final bit of cooking. As opposed to turning the heat off when cooking is completely done.
    - graeme 5y ago
      Precisely that
- toastal 5y ago
  Funny that the Maillard reaction causing browning and using the resulting fond is exactly what you want to see and eat from a culinary, tastes-good perspective.
Exuma 5y ago
What sensor do you have? And what is the boxfan hack? I live near very bad wild fires and I need a much better filtering then my current grow filter which doesn't seem to work that well.
- johntash 5y ago
  > And what is the boxfan hack? Literally just a box fan w/ a hvac filter taped to it. There are a few articles/youtube videos where people claim it works a lot better than a fancy air filter+fan device that costs $100s. If you try it, just be careful it doesn't burn the fan motor and/or cause a fire.
- bryceacc 5y ago
  https://www.youtube.com/watch?v=kH5APw_SLUU https://www.youtube.com/watch?v=kH5APw_SLUU you just put a fan filter on the back, you can increase the amount of filters to not hurt the fan motor as much by making a triangle config or fan on top of 4 filters in a cube. fans are for air throughput not static pressure so real air purifiers have squirrel cage blowers
teekert 5y ago
Yeah the cooking indeed. My parents have a Philips air filter, when they cook or turn on their AirFryer or even when lighting the bbq outside, the thing's led-ring goes from blue to red and it starts to work very hard. It thought that was pretty striking. I usually do the cooking at home, now I wonder if I'm going to have a shorter life compared to my wife :s

Someone1234 5y ago

> I didn't even bother taping the filter to the fan. I found bungee cord with J hooks works really well. As you correctly point out, you don't need to secure it at all, but it is annoying to tap the box fan and have the filter fall over.

lisper 5y ago
That seems odd to me. I've never tried this, but it seems to me that you have to put the filter on the intake side of the fan, other the fan would just blow it off. And on the intake side, would not the pressure differential hold it in place?
- wholinator2 5y ago
  I feel like you could place it on either side of the fan as long as air is directed to go through it. My personal intuition is filter then fan but I don't see a reason it couldn't go the other way. I wonder why most devices place it on the intake though. Maybe to prevent dust from getting inside a device, but even then it'd only protect the fan from dust. Hmmm...
  - johntash 5y ago
    Fan and then filter could lead to the fan blades getting dirtier faster. Other than that, I'm not sure if it makes a difference as far as effectiveness.
- late2part 5y ago
  Good on you, master of the obvious!

rtkaratekid 5y ago

What sensor are you using? Just curious.

tpmx 5y ago
For DIY, there was a pretty good discussion on suitable sensors in the AirGradient post from three months ago that Jeff linked to: https://news.ycombinator.com/item?id=27125060 https://news.ycombinator.com/item?id=27125060 tl;dr: seems like you want an NDIR sensor (https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor). Some options, with digikey @1 prices: Senseair S8 (Sweden): $48 Sensirion SCD30 (Switzerland): $63 Amphenol Telaire T6713 (US): $96 If I were to buy an expensive black box iot solution, I'd at least verify that it had an NDIR sensor.
- s0rce 5y ago
  I'm using an SCD41 with an OLED+microcontroller (using Sensirion's example code hacked a bit) and it seems to work well, cheaper than the NDIR using some photoacoustic magic.
  - tpmx 5y ago
    $37 @1, but not in stock at digikey, and an 11 week lead time. It's pretty tiny... I wonder if/when it will be possible to put a high quality co2 sensor in an IP68 iPhone...
    - s0rce 5y ago
      I had purchased the dev kit sek-scd41 but its out of stock as well. The SCD41 also does RH and T so you don't need a separate sensor for that.
macNchz 5y ago
I'm using an Awair Element, I didn't do a ton of research on alternatives, but the app is pretty good and it "just works".

Scene_Cast2 5y ago

I think the draftiness is key. In my findings, in a "modern" house (double-paned windows, built in the last 20 years), sleeping with the door closed will spike CO2 to 4 digits. The other thing is that air really needs to circulate in order to lower CO2 - opening a window in a room will not lower the hallway CO2 unless there's at least some draft / air movement.

5e92cb50239222b 5y ago
Temperature difference helps if there's no wind. In winter time CO₂ drops from 4000+ ppm to ~450 in only a couple of minutes after opening a single window (with inside to outside temperature difference of 50°C or higher). In summer it drops to ~600-700 and stays there, and even this takes hours.
- y4mi 5y ago
  50°C difference or even higher? Damn mate, even Siberia only gets around -34°C which is less then that of you target the usual 18-21°C. Your winters sound terrifying.
  - theluketowers 5y ago
    Saskatchewan Canada can easily reach -40°C for several weeks during the winter.
    - JamisonM 5y ago
      What? Maybe in the most northern reaches.. even then "for several weeks" is a stretch.. even Uranium City doesn't hit -40°C every winter!
      - bbarnett 5y ago
        There is often confusion between wind chill, and actual temps. But the parent is not inaccurate, for they did not mention "each year". Even 10 minutes North of Ottawa, I saw -42C, real, not just windchill, for a week, about a decade ago.

goodpoint 5y ago

> - Cooking is insanely bad for the air in your house Hold on! Not all particulates are equally harmful - and by far! A particulate sensor detects water vapor or particles of (non-burnt) cooking oil that are harmless to humans. In the same way, it detects very dangerous (carcinogenic) compounds from combustion engines or burning coal or wood. Cooking is in no way "insanely bad" (unless you are grilling your food black or cooking on an open wood/coal fire)

5e92cb50239222b 5y ago
It does not measure water vapor, at least not the one I'm using (PMS5003). I always have windows tightly shut because of the extreme pollution outside, so 100% humidity is easy to reach simply by mopping the floors (which stay wet for hours after). It does not change PM measurements one bit. Fry a couple of eggs though, and PM 2.5 quickly goes over 100 µg/m³. Burn a piece of meat just a little bit and see it rise over 300 µg/m³.
- eutectic 5y ago
  What about suspended water droplets?
crazygringo 5y ago
The thing that sends my PM2.5 skyrocketing the most is, interestingly, my toaster oven. Like from 50 to 1500 in the space of 10 min. No food needed within -- just the heating itself. I have no idea what the particles are though -- metal? Paint? Carbon from burnt residue? Or just whatever the heating element itself is made of? Separately, cooking with gas (oven+stove) also sends CO2 way way up -- in my kitchen, from 500 to 1300 or so within 20 minutes. And that's with my range hood on.
- thrashh 5y ago
  Dust in the toaster?
- sneak 5y ago
  A lot of range hoods don't actually exhaust outside, and just suck stovetop air over some steel wool to condense the grease particles somewhere other than your walls. Not saying that's the case here, but several times I thought the range fan was exhausting the air, only to learn upon examination that it was just shooting it back out into the same room.

r00fus 5y ago

When the air is good outside, I typically run our whole-house fan pulling in outside air while I'm baking or making dinner - didn't consciously decide on it, but it just seemed to feel better to do those together. Now I really need to investigate more details - like does induction cooking (vs. gas) improve the quality? What about the type of food (ie, cooking vegetarian vs. grilling sausages)?

beenBoutIT 5y ago
Investigate fume hoods and implement a good one with enough make-up air to take everything coming off of your range out of your kitchen. Air quality's negatively impacted by heating pots/pans/etc. and their contents up and less about how they're being heated. With the exception of h2o just about everything you cook has a negative impact on the air quality and the pans themselves are doing all sorts of interesting things to the air when they get hot.
- velosol 5y ago
  I agree on PM2.5 but gas is clearly worse from a CO2 (and other combustion byproducts) point of view compared to induction which is limited to 'just' the food items and the containers they're in.

nsporillo 5y ago

The box fan and high-merv filter hack is a good idea, but proper ventilation of filtered outdoor air is the best solution. Not always practical, but historically buildings breath via air infiltration due to pressure differentials, stack effects, wind, etc - might as well bring in the air on your own terms rather than it leak through your walls and insulation.

Tenoke 5y ago
I'm not actually sure it's always the best. My rooms face the street and I can't tell if the air I get on that side is actually better than just having air from the other side +purifier.
- nsporillo 5y ago
  Quality Energy/Heat Recovery Ventilators (which are basically mandated by code [in some jurisdictions] in modern construction due to air tightness requirements) should allow you to select the filter with the MERV value that works best for your situation. But to be fair, you may have a good point. Vehicle emissions and tire wear generates particulates consider to be ultrafine (0.1 max nanometer), which is even difficult for HEPA filters to deal with.
macNchz 5y ago
On my leafy Brooklyn street the particulate pollution outside is well within the recommended levels nearly all the time, so thankfully there's not really a pressing need to retrofit modern ventilation into a 120 year old house. That is, assuming the presence of wildfire smoke from 3000 miles away remains a rare event, which...who knows.

karmelapple 5y ago

Agreed with all these observations, especially gas oven or stove usage! Our former third floor ~1200 sq ft condo would spike CO2 up well over 1400 ppm when we’d run it, and almost instantly. Even just with two people working from home, much of the space would quickly get up to 800 or 900 ppm. I’d usually open windows as I saw it creeping up, which would quickly reduce CO2 to under 600, and then it would slowly creep up over the day.

wintermutestwin 5y ago

>The 20" box fan + MERV furnace filter hack Living here in the west with hyper toxic AQI for the better part of two months now, I decided that the low CFM and leakage of a DIY box fan are not adequate to keep up. I went with a far more industrial solution: I went to an indoor grow shop and bought an activated carbon filter and high CFM inline fan. Cost $150 and is a bit noisy, but has been well worth it.

fosk 5y ago
Link?
- wintermutestwin 5y ago
  I wouldn't recommend this specific setup, but these are the type of filters/fans I am talking about: https://www.amazon.com/VIVOSUN-Inline-Controller-Ducting-Ventilation/dp/B07YZKWNG5/ref=sr_1_7?crid=I4OFRYHOPKQC&dchild=1&keywords=carbon+filter+for+grow+tent&qid=1631143912&sprefix=carbon+filter%2Caps%2C298&sr=8-7 https://www.amazon.com/VIVOSUN-Inline-Controller-Ducting-Ven...
jonahhorowitz 5y ago
You can buy carbon activated MERV filters. I got some from Nordic Pure.
Exuma 5y ago
what MERV rating is that. I do that now but I thought it's MERV 8 which really won't remove much at all
rsync 5y ago
I’m surprised to hear this - a standard box fan from ace has something like ~600 cfm, right ? That’s fairly high - what is the size and cfm of the fan you bought?
- wintermutestwin 5y ago
  Not when you strap an HVAC filter on it. My setup is ~600cfm with much more filtering. Not sure what the MERV is but the cylindrical layer is much thicker and heavy duty than an HVAC filter.

throwawaysea 5y ago

There are better setups than the 20" box fan + MERV furnace filter. For example check out this similar DIY design that reduces risk of an electrical fire by making it easier for the fan to draw air: https://encycla.com/Corsi-Rosenthal_Cube https://encycla.com/Corsi-Rosenthal_Cube

rovr138 5y ago
From that page, >The EPA funded a study by Underwriters Laboratories (UL) which tested box fans with MERV-13 filters attached, finding them to not present a fire hazard even in extreme, modified conditions. Then it links to, https://chemicalinsights.org/wp-content/uploads/DIY-Box-Fan-Report-2021.pdf?utm_source=Chemical+Insights&utm_campaign=d52ba63ea8-July_2021_Newsletter7_13_2021_13_4&utm_medium=email&utm_term=0_09fecf83d2-d52ba63ea8-119531236 https://chemicalinsights.org/wp-content/uploads/DIY-Box-Fan-... which says, >Two-Sided Obstruction >Figure 6 shows the time series of monitored temperatures under extreme condition where both sides of the fans were blocked. Despite the severe blockage of air flow, temperatures of all five box fans peaked within the first 20 minutes and then plateaued, remaining steady for the remaining 7 hours. Winding temperatures had the largest relative increase of 30 to 57 °C above ambient temperature, with peak absolute winding temperatures remaining at or below 80 °C. Peak temperatures on other fan parts did not exceed 50 °C. > Temperatures at the power cord, guard, and switch, remained close to ambient room temperature (±6 °C) during all filter test scenarios as well as during the one-sided blocked tests. For the two-sided blocked tests, temperatures at the power cord, guard, and switch increased initially before plateauing to a steady temperature for the remainder of the 7-hour test duration. All fans remained operational for the 7-hour test duration and did not show any signs of potential hazard or damage.

tootie 5y ago

Not an expert but from what I've read, gas stoves are by far the worst. Electric (including induction) are much healthier.

TrevorJ 5y ago

The gas stove thing was surprising, but of course it makes a ton of sense!

jeffwass 5y ago

If someone knows the answer to this I’d be interested to know : Do different PM2.5 components affect the body differently, even for the same overall count? Eg, are the PM2.5 particulates from burning toast comparable in bodily health impact to a similar PM2.5 count coming from a heavy Diesel engine’s exhaust (which I presume would have a different particulate makeup).

pirate787 5y ago
My understanding is that PM2.5 with heavy metals or toxic payloads is more dangerous, but both are dangerous.
pyk 5y ago
Still an active field of study but your intuition seems to be right. One study is here [1]. Combustible “types” of PM are usually worse (think smoke / carbon) vs. vaporous types of PM. The method of action is hypothesized to be the carbon particulate getting lodged in your lungs (similar problems from smoking, carbon nanotube inhalation, or charred foods). [1] https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.0800185?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.0800185?url_v...

jozzy-james 5y ago

- Cooking is insanely bad for the air in your house, even with an outside-venting hood. weeps in searing steaks with no hood at all :'(

bfirsh 5y ago

One thing I found is our furnace fan and its filter is surprisingly quick and effective at cleaning up wildfire smoke (and cooking smoke...) https://twitter.com/bfirsh/status/1434677458171678721 https://twitter.com/bfirsh/status/1434677458171678721

graeme 5y ago

> Cooking is insanely bad for the air in your house, even with an outside-venting hood. Any sort of medium-high heat cooking will spike the PM2.5 to multiple times that of the haziest days here in NYC, and with the windows shut it will stay elevated for hours after. I’ve found this varies quite a bit. Though, I don’t do a ton of high heat cooking, so maybe there’s no way to do that without pollution. But at medium to low temperatures, you can get crazy variance in AQI output: * Lack of enough oil/butter in the pan will send levels soaring * Cooking one thing in the pan then another after is very bad. Eg I used to cook sweet potatoes then add meat after and not clean in between to save waiting. Boy was that bad for the air. I think it’s because tiny bits of food you may not even see stick to bottom of pan and burn * Browning is when it gets worse. Any kind of browning on foods spikes pollution. * Any food particle that gets on the burner will invariably lead to hazardous AQI levels. Like even a single fleck of meat left cooking will fill the house. You may not necessarily smell it as much as other things * Turning heat off at end of cooking works wonders. I do this with bacon and it takes it from a hazard to not even spiking aqi. Finished product looks and tastes the same

faeyanpiraat 5y ago
"Turning heat off at end of cooking" What is the alternative?
- Sander_Marechal 5y ago
  I think he means that you turn the heat off before cooking is finished and let the residual heat of the pan do the final bit of cooking. As opposed to turning the heat off when cooking is completely done.
  - graeme 5y ago
    Precisely that
toastal 5y ago
Funny that the Maillard reaction causing browning and using the resulting fond is exactly what you want to see and eat from a culinary, tastes-good perspective.

Exuma 5y ago

What sensor do you have? And what is the boxfan hack? I live near very bad wild fires and I need a much better filtering then my current grow filter which doesn't seem to work that well.

johntash 5y ago
> And what is the boxfan hack? Literally just a box fan w/ a hvac filter taped to it. There are a few articles/youtube videos where people claim it works a lot better than a fancy air filter+fan device that costs $100s. If you try it, just be careful it doesn't burn the fan motor and/or cause a fire.
bryceacc 5y ago
https://www.youtube.com/watch?v=kH5APw_SLUU https://www.youtube.com/watch?v=kH5APw_SLUU you just put a fan filter on the back, you can increase the amount of filters to not hurt the fan motor as much by making a triangle config or fan on top of 4 filters in a cube. fans are for air throughput not static pressure so real air purifiers have squirrel cage blowers

teekert 5y ago

Yeah the cooking indeed. My parents have a Philips air filter, when they cook or turn on their AirFryer or even when lighting the bbq outside, the thing's led-ring goes from blue to red and it starts to work very hard. It thought that was pretty striking. I usually do the cooking at home, now I wonder if I'm going to have a shorter life compared to my wife :s