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.
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.
In a modern home, there should be supply and return vents in every room. My home built in 1978 has 3 returns for the entire house, one on each floor. Master bedroom has a supply, but the return is located in the hallway. Over the years, the recommended door cut to allow air flow has been changed (presumably for greater privacy) - which leads to the scenario you're describing.
I could add the door cut back in, install return transfer grill, or look into adding a secondary heat recovery ventilator that acts independently of the primary HVAC system.
I know many people who put 'draft stop' devices on the bottoms of their bedroom doors in older homes (old enough to not have returns in each room, but new enough for central air), not realizing they're cutting off the one bit of circulation they need for a proper functioning central air system!
Or they buy new high efficiency windows and doors, and that 'tightens up' the house, but they don't also install an HRV (Heat Recovery Ventilator) to exchange outside air.
Realistically new windows and doors probably wont drop the homes air changes per hour below the recommended minimums, but I don't know for sure. I've gotten my crawlspace spray foamed and I'm getting my vented attic spray foamed to bring it into my envelope. Also getting new windows and doors soon, but after all of that I think enough air could leak through sill and top plates, electrical outlets, etc.
Having the foam crew do a blower door test for free if we go with them, so I guess I'll see. I live in climate zone 5a (cool, humid) so historically natural ventilation was used via induced pressure differentials generated by mechanical means (dryer, furnace, bathroom and kitchen vents). When we get new furnace and water heater that pull combustion air from outside, we're left with mostly manual means for generating negative pressure that drives infiltration. (But also wind, and pressure differentials caused by temperatures in winter)
In our case, we're definitely considering either an HRV or ERV to supply fresh outdoor air that we control (input and output CFM, MERV #). Our indoor air quality is poor enough to the point where we live with the tangible symptoms (Rhinitis), not just numbers on a sensor.
For those with interest in these topics, I suggest skimming a copy of one of the ASHRAE fundamentals handbooks[1]. It reads as a textbook but has incredible depth into the physical sciences that relate to building science, heating, cooling, and ventilation.
> In a modern home, there should be supply and return vents in every room.
That must vary by region. I live in the PNW, and I have not seen a recently built house with a return in each room. One or more supply vents per room depending on size, one return for each floor seems pretty much standard.
Interesting. I live in the upper midwest and remember my first home I lived in (parents built it new in 1980) had returns in every room. My current home is primarily forced air and there are returns in every room with multiples in the larger gathering spaces. Was built in the late 90s and I think building code may require a specific number of returns per square foot.
Could be regional -- I would bet that in most cases houses in the upper midwest have to deal with much colder temperatures in the winter than houses in the PNW. Maybe that influences the HVAC design.
But I wouldn't be the least bit surprised to find that there isn't really a specific reason, it's just "how we do things in this area." A surprising amount of building choices seem to be made that way.
Over here in Finland, nobody has returns in each room. It's a cold climate, so houses are heavily insulated, and moisture condensation is a concern during the winters.
We typically have returns in toilets, showers, etc. with one or more supply vents in each room; a large room may have several. Air flows in via supply vents, flows out under mandatory gaps in doors (if closed), through to the toilets and then outside. Moisture, CO2, and smells are constantly flushed in the right direction.
When the hood is on for cooking, air supply is typically enhanced so it doesn't mess up the overall pressure too much.
Incoming air is filtered, of course. The ventilation unit transfers heat from outgoing air to the incoming air to save energy and avoid problems with condensation.
In my home office, TVOC as measured by an Eve Room rarely goes above 100 (mostly happens when I pour an occasional whisky in the evening).
Old houses don't have ventilation machines at all, but rely on natural ventilation instead: warmer air flows upwards via chimneys and such due to gravity, pulling in fresh air from whatever gaps the structure has (accidental or purpose-built).
In the last decade I built 2 houses in the same neighborhood over 6 years. The first didn't require a return per room and the second one did - they had changed their code. A few years later and they had reversed their decision.
I guess the point is that it depends on when and where something was built. My most recent home is only a few years old and doesn't have a return per room and no code to say it should shouldn't.
A 1" door undercut is only about equivalent to a 6" duct in cross section and that size should max out at 120 ft^3/min with well installed duct. If you have more supply then there will be airflow issues in that room/house.
Our multi-room apartment in Redmond, WA, has an always running intake fan in the master bathroom advertised as a way to keep air fresh. I always wonder how effective that really is (at apartment scale) and if it's really worth the 24/7 power draw.
Almost certainly designed to ASHRAE 62.2's specs so that you get enough ventilation through a combination of infiltration (leakage) and additional mechanical ventilation. It's certainly worth it and if designed as a continuous ventilation fan should be one of the lower (~15W) draw units. Not sure how to really measure effectiveness other than by trusting in the experts who came up with the spec and air quality as an indirect measure.
It's to keep positive pressure in your unit for safety purposes. If there is a fire the fresh air will help keep smoke out of your unit and as a bonus it keeps other building odors out. Generally it is a large fan on the roof that just sucks air down a stack pumping it into every unit. You could put a filter over the register and filter that air.
Sorry, by intake I meant it's sucking air in. That is, air is leaving my apartment. I think you're on the right track with the safety angle here though. Will do more research.
I bought my parents a Netatmo weather setup. The one in the house measures temp, CO2 and the one outside temp, humidity.
During Christmas Day visits with only a half dozen people the room CO2 spiked to over 1,000ppm. Older house from the 1970s no HVAC. Opening a window (cross draft) brought it down to 300ppm. The room was stuffy before and great after so it shows how sensitive we humans are to air quality.
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.
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.
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.
That's what I've discovered over the past year! I live in NYC and my CO2 levels are fine in both the winter and on hot summer days, without even trying.
But when it's 65-75°F outside in the spring/fall... CO2 builds up in my apartment like crazy. I keep the windows open and my bathroom fan on to try to suck fresh air in... but even so can't manage to really get it below 650, and with just a window cracked it sticks around 850.
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.
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.
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.
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.
I am able to find many journal articles confirming my observations that cooking produces significantly elevated indoor PM2.5 levels, many of which suggest it to be harmful, but I'm not finding anything about the relative impacts of the different substances that make up fine/ultrafine particles. People involved in this research seem to think it will require more study:
>“We know that inhaling particles, regardless of what they’re made of, is detrimental to health. Is it equally bad as inhaling exhaust from vehicle emissions? That we don’t know that yet,” [1]
Regardless, my sensor, at least, doesn't register water vapor as particulate. I can run an ultrasonic humidifier with distilled water to no effect on the measured PM2.5, or with tap water which will spike the particulates from the dissolved minerals.
You're leaving out the most important part: cooking with gas.
"Natural gas and propane stoves can release carbon monoxide, formaldehyde and other harmful pollutants into the air, which can be toxic to people and pets."
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.
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.
The last place I lived in - the cooker hood did exactly this, without even the steel wool. We noticed a growing stain on the ceiling and found out there was no outlet, no filter, just a fan blowing the greasy air onto the ceiling. This was a 1 bedroom apartment with one of the ubiquitous "kitchenette"s that are fitted these days, so that landlords don't lose a whole room to a kitchen that exhausted commuting professionals will never use.
Our current place has a proper kitchen, but the cooker hood vents outside directly next to the central heating boiler's intake.
Thing is you can't really deep-clean it... it's not particularly dirty, I keep the bottom free of crumbs etc., but when oil droplets from food collect against the back surface and polymerize there, what can you do...?
You can't exactly throw the toaster oven in the sink and scrub the inside surfaces with steel wool and Barkeeper's Friend under running water like you can with pots and pans. Nor do toaster ovens have a "self-cleaning" cycle where you try to just vaporize it all... they simply don't get hot enough.
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.
i mean, i'm on an electric stove - and i have a cloud of oil/smoke when i properly sear stuff, given i have no ventilation outside of a small window. can't imagine that's too good.
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).
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).
> 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
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.
Totally. It is possible that a better cook than me can thread the needle of producing such a reaction without producing much pollution.
I haven’t tested AQI with steak for example. And I can say that with bacon I have certainly managed to have it turn brown without pollution. But, once things are turning brown you are on thin ice and it is easy to go from “none” to “hazardous” in a flash.
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.
> 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.
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?
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...
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.
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.
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.
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.
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
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.
Like you, and for the same reasons, I recently bought an Awair. At the risk of a derail, one thing I have been thinking about ever since: when I played D&D as a kid, they said the difference between Intelligence and Wisdom was, "Intelligence is knowing that it's raining, Wisdom is knowing to go inside." How much of these things are adding to our intelligence without adding to our wisdom? I am now constantly aware of particulates and everything else it cares to send me alerts about (which I will soon shut off) but how much better off am I once I established my air quality is basically Very Good.
The problem with all this "intelligence" is the Internet is very good at showing you search results for what you want to see, so Googling "Should I be worried about fine particulates" is a search destined to turn your anxiety into a full-blown panic attack.
No idea what the answer is, and I am impressed with the level of effort that went into the Awair app, but it would be nice to have more reasonable context in all IoT devices. Yeah, I know.
I definitely see where you’re coming from. When I first got it I was freaked out by the frequent spikes of VOCs, before determining that it’s actually hypersensitive to farts. I’ve come to ignore most transient fluctuations and just use VOCs/CO2/PM as guides for when to open or close the windows.
I’ve also found that regularly glancing at the 5 minute resolution charts of just temp and humidity has helped me get a better sense of my own comfort range…for example I like to run my AC as little as possible in the summer, but I’ve learned that playing chicken with the heat is foolish beyond 81F as I only wind up sitting at my desk grumpy and unproductive.
I've been thinking of getting it what are your thoughts on longevity of it? Will it last at least a few years? I also see in some Amazon reviews that measurements get "stuck" to some extreme. Have you noticed that too?
I've had an Awair Element for about 16 months. The only time I've experienced what you may mean by "stuck" measurements was about a month ago, when PM2.5 was puzzlingly and worryingly at a consistently higher than usual level for a couple of days. Trial and error eventually suggested that there was a piece of dust stuck in the sensor or something like that. Upon blowing on the sensor, the measurement returned to normal.
After a year I don’t see any issues with it, the sensors don’t seem to have drifted or changed in their responsiveness at all. It has crashed once or twice and stopped responding but was fine after a power cycle.
With any IoT device I’m wary about longevity re app support, I can’t say how long Awair will support this device or whether they’ll provide access to it after they stop, but I’m less concerned for a device like this vs, say, a major appliance.
Are there any affordable CO2 sensors that don’t use outside air for calibration of ppm? I want to know how outside air CO2 levels change as well. Would be interesting to see day to day changes and how big they are in absolute terms. (Also to show people about how CO2 levels are changing globally… without just pointing to a website of someone else’s measurements.)
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)?
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.
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.
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.
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
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.
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
>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.
>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.
I did a similar thing -- set up AQ sensors in the house.
I used the sps30 from sparkfun, CAD'd up a panel mount, 3d printed it, built a wooden box for it + a pi, set up all the networking and hosting, and packaged my utils for debian.
Anyway, the AQ is fine, HEPA filters work when in-line with the A/C, and there's nothing much to monitor even when AQ is mod/bad outside. Boring, but nice to know, and fun to learn all those new skills.
That has been my experience too - unless you put your monitor in your kitchen, in which case frying or baking will usually cause a pretty significant spike...
I bought some electric candles. They can go months on a AA nimh battery, and if you pay enough for them, they are actually good / realistic enough for the wife's relaxation. Great for power outages as well.
I like fire, and I like dripping wax, and I have really nice sterling candelabras that look quite spiffy on my big table bedecked with a half dozen long black taper candles.
But I just like the 'ambiance' too much. There are always different levels of risk adverseness: if I was considering candles a pollution health hazard I should also stop riding motorcycles, vaping various things, and stop eating like I do...
These work really well, and seem to actually be made of wax so the candle looks quite good. Note the "wick" is sunk in an inch or two so there's nothing to really suspend disbelief.
Also they have an optional 24-hour timer so they'll remember to turn on the same time you turned them on yesterday.
> the components for this project cost between $60-80
Purple air sells a turn key indoor air quality device for $200, is very reliable, also comes in a (clear) 3d printed case, comes with power supply. Not as DIY as this guy's solution, but with limited time on my hands the $100 was worth the cost of admission. It also works with Purple Air's map which provides nationwide air quality, temp and humidity, etc which is really nice.
It's worked flawlessly for me now for about five months. The light turns from green to yellow when I open the window in my south facing condo, but turns green again when I close the window and turn on the air filter. I was surprised at how bad the air quality gets when cooking food on the stove.
> But after a few weeks, and after adding in a manual temperature adjustment to compensate for that sensor's inaccuracy, the AirGradient has been a very stable and helpful addition to my home environment monitoring.
When you are DIYing this sort of thing, I would think you would need to make at least a couple of them to see if they calibrate to the same measurement, assuming what you are after is greater precision and control (why else would you DIY it?). Even then, both devices could calibrate to the same very imprecise value.
To really validate this, you would need to put it in an controlled environment with known air pollution levels. Just placing it outdoors when the weather report says 200AQI wouldn't work since that's an average over a large area, not a point measurement.
I imagine the sensor manufacturers have done some calibration - the article mentions a self calibration period for some, but once everything is in the final package, I'd expect the behavior to change.
I have two identical boards now, along with my TemTop portable unit, and the CO2 is quite close (< 1% difference usually), and PM2.5 readings are more like 5-10% different. The temperature is the biggest outlier, but I need to figure out a better placement for the temperature sensor to get that issue fixed.
yup. not entirely useless, but especially for the borderline yellow/orange AQI you want to know the error.
http://www.aqmd.gov/aq-spec tests and compares commercial AQM vs lab grade instruments. It isn't quite enough to compare a commercial unit with the same sensor, because you don't really know the mfr calibration (if any), but this will get you a much better idea of performance.
i personally prefer to have a commercial sensor that has an API, rather than DIY.
Yes, but has the final assembly been calibrated against a known controlled environment?
Without that, the readings from the device become more of a crapshoot, which is fine if there is no desire for greater precision (i.e a just for fun project)
Sensor manufacturers cannot calibrate for every possible packaging configuration.
As someone who has DIYed a lot of stuff related to indoor climate, I tend to save my effort for the mitigation work, and use well tested measurement tools to validate those. This is for the same reason that one doesn't usually DIY a multimeter before doing electrical work.
The PM sensor I’m thinking of comes in it’s own packaging with a fan, and is usually attached to a PCB alone. I don’t see how most applications of it would require a recalibration.
Is there a good non DIY air quality monitor that can be hooked up to Prometheus for monitoring over time?
I know this is a very “non HN” thing to ask. But, as much as I’d love to learn and tinker with Adruino, sensors and their soldered connections, supplying power correctly etc, I am afraid all my spare time would be gone to it, and I will never get to the air quality part of the project. It will be yet another wide scoped project that never ends. Hence the ask for a non DIY yet Prometheus compatible solution..
The huawei are filters have integrated sensors and with a bit of hassle the info can be extracted. Some people don’t like huawei gear but I’ve found the hardware at least to be good
I found something on AliExpress that seems to send data over Bluetooth. I don't what kind of effort it would take to capture that data if I have a RaspBerry Pi with Bluetooth.
The huawei stuff is generally addressable via LAN using home assistant etc.
Can be a bit tricky to get hold of the security tokens but at least doesn’t involve re inventing any wheels. One is very much at the mercy of firmware updates blocking diy access. General recommendation is not to update.
Plus US crowd is pretty paranoid on huawei stuff ofc
Well, I am not planning to let my air quality monitor connect to the internet, let alone to my home network where my computing devices are. So, there’s that.
If the huawei thing is accessible in the local network, that is almost exactly what I want. I can connect it to a raspberry Pi on an isolated network and extract the data I need. Thanks for the tip.
This doesn't answer your question - but in all seriousness you can smell it. Even the smallest amount of ozone has a very distinct smell you will recognize. If you stand in front of your air sanitizer and let the air pass over your face, you should be able to smell the ozone immediately.
If you haven't smelled it before - I would recommend going to a retail store that sells ozone-based air sanitizers. That should give you a whiff of the stuff for reference. You can also find it in [some] hospitals for air sanitization. I imagine once you smell it, you will realize you have smelled it before and maybe not realized it was ozone that you were smelling.
I know what Ozone smells like (I remember the old laser printers that were also effective ozone emitters), but trust a sensor more than my ability to smell low levels of Ozone.
My air purifier is built into the furnace ductwork so it's already pretty diluted air by the time it comes out of a duct.
> My air purifier is built into the furnace ductwork
That's neat! Do you know if the ozone is produced before or after it reaches the blowing mechanism? I ask because if it is produced before, like right after the air intake, that's a really great setup for keeping your ductwork mold and mildew free. I've wanted to buy such a system but keep holding out for things to get cheaper... in the meantime, I use an ecoquest "FreshAir" model sitting on top of the fridge.
Not sure if this is DIY enough for you, but I'm using an MQ131 (about $20-$30 on Amazon, probably cheaper directly from China [1]) in an air quality monitor I'm building. There's an Arduino library for it [2], and from what I can tell so far, it does work, though it's probably not super accurate. It's also somewhat sensitive to environmental factors, but you can correct for some of that with known temperature/humidity.
[1] There are a few different kinds of MQ131 (for high and low concentrations); you'll probably want the low concentration one. I also removed the bare sensor from a breakout board I purchased so I could access it directly from my custom PCB.
That's exactly what I'm looking for, looks like I can get a $30 MQ131 with detection a range of 10PPB-2PPM [1], and a "Good" indoor level is 0 - 54ppb [2]. It doesn't need to be super accurate for my use case, basically I just want to turn on the electronic filter and see if there are any detectable levels of Ozone.
Could anyone advise of the best way of getting hold of the PCB? Looking at the air gradient webside they provide "Gerber files", do these need to be sent to a PCB manufacturer to create? If so, does anyone have recommendations of which to use? It is something I would like to learn about but I am rather new to.
KiCad for design and JLCPCB or FusionPCB for manufacturing has been good enough for me to go from nothing to a completed board. Yes, gerber files are equivalent of “compiled binary” that you send to a PCB manufacturer to be printed.
Bought a monitor because aqi near me averages 50-100 during summer, pre-fire season.
Found my tvoc is constantly in .70-1.0 mg/m3 unless I open all windows and run fans. Then it drops to around .6 mg/m3. I now don’t worry at all about pm2.5 levels and just keep my windows open if the temps below 100. Buying the monitor showed me that my migraines and other issues (brain fog) were caused by the high voc. Opening windows even if it means breathing wildfire smoke makes the headaches disappear.
Anyone out there on the fence about buying a monitor, just do it. There are worse issues than pm2.5 and smoke, both of which you can detect with your nose.
Just the 80 dollar temtop that sells on Amazon. Easy enough to check against local purple air sensors for the particulate readings. I did that, and they were spot on for my neighborhood. Don’t know if I trust the formaldahyde reading but the tvoc corresponds to my physical experience very well, and it drops to near 0 tvoc when taken outside. If there’s a catch, it’s that you don’t know what voc you’re dealing with. Could be something lethal like radon or something fairly innocuous at the levels I’m seeing. Whatever it is in my case, it causes very predictable migraine symptoms which correspond to the voc level almost perfectly.
"The case is well-ventilated, and my only complaint is the natural convection causes very-slightly-warmed air from the WeMos D1 and CO2 sensor to pass over the temperature and humidity sensor on the top, meaning those readings are always a bit higher than ambient—at least in my office."
But then the display would not be oriented correctly ;)
What I'm planning on doing is soldering a jumper to the board and having the temperature sensor hang out the side of the case a bit, towards the bottom.
My old Awair has a Telaire T6703 CO2 sensor; the newer ones probably have something similar. I also had a standalone sensor at one point, they're a thing too.
And Tindie has a slew of ready-to-order air quality stations too.
Have you had a good experience with Awair? The last time I looked it seemed like they had no recommended way to clean the sensors. And in my limited experience PM2.5 sensors do need periodic cleaning to remain accurate. My air filter has one and the manufacturer recommends a bit of alcohol and a puff of air.
Their old one had an issue with the dust sensor clogging.
The new ones use the Honeywell sensor. It has a tiny fan on it (inaudible in a quiet room from 5 inches away); mine ran well for a couple of years until I knocked it off my desk. After that, the fan started rattling, so I ordered another Honeywell sensor ($40) and replaced it (no soldering required, just a screwdriver). That sensor's datasheet doesn't have any cleaning instructions, so I don't think it's a big issue.
Probably worth noting that the South Coast AQMD tests various PM sensors from consumer-grade to lab-grade and publishes results [0]. Lots of cheaper consumer-grade sensors outperform the expensive lab-grade sensors.
Plus, my living in Canada means getting all the different components piecemeal, often from different suppliers/sellers is a giant PITA. This is further complicated by my self-imposed restriction to not buy from Amazon. And this is before the headache of shipping costs (often $15 as the lowest option, even for small parts)
I'd love a ~$200-300CAD pre-assembled or kit option where I can own the data, access it in a standard fashion, and optionally choose to crowd-source it.
I'm currently building an adapter to mate furnace filters to quiet, high static pressure fans. This should keep the same volume of filtration as a box fan, but lower the noise significantly. I'll probably be ordering a batch of 5-10, if interested, email me (link in profile). Or comment, as long as you have an email in your profile, I suppose.
I can recommend against one type of bad sensors. VOC sensors paired with a temperature sensor that can generate “eCO2” value is known bad, such as CCS811/BME280 combo board.
Those sensors guesstimate CO2 concentration from air temperature and changes in ambient alcohol/acetone/hydrocarbon levels, which drifts into positive infinity and is simply do not correlate well with actual CO2 level.
Those sensors are dirt cheap, and can still be used as a rule of thumb to encourage regular ventilation, but are nothing more than that. If you want to actually see CO2 levels, avoid those.
Not exactly inexpensive. These are "low cost" in that they don't cost $20,000 like the sensors used by government agencies, but they aren't what I as a consumer think low cost means.
Is there a non-DIY version of this, preferably <$100? I often have breathing difficulties and would be curious to see if humidity, CO2, and pm2.5 are affecting me, but I don't have a soldering kit.
I backed the Kickstarter for bluSensor last year, and have been happy with the device so far. The app needs a little work, but makes it easy to check current and historical air quality.
It has 4 sensors: temp, humidity, CO2 and VoC. Helped me discover a problem with my attached garage leaking fumes into the house.
Any suggestions for a CO2 monitor that doesn't require you to solder? I have an Arduino and a breadboard so can hand wire things in the meantime if needed...
In theory there's no reason you can't use a breadboard jumper kit and splice it to the cable that the sensor comes with
But soldering has a very low cost-of-entry, and even using solderable breadboards over solderless can make your project a lot easier to use (no more worrying about lose connections or capacitance issues)
I really like my Aranet4, although it costs a little over US$200. No soldering though, and its been running on one battery charge for over half a year!
I was surprised to learn that the Airthings Wave Plus ($180~) doesn't measure PM2.5. It is cool that it does Radon and VOCs which this cannot do.
This seems like it could either compete OR complement an Airthings Wave Plus for like 35% of the cost. Since they both offer different and overlapping data.
I wonder what you'd need to do to get Radon and VOCs too in this solution (essentially match and exceed the Airthings Wave Plus)?
Last time I looked into gas sensors (for measuring SO₂ and NO₂ which reach extreme levels in my area), they were $100+ each, depending on the gas it's measuring.
Have you looked at the View Plus (€300-ish)? It has PM2.5, CO2, radon, humidity, pressure and temperature. Also I believe it has multiple of some of the same sensors for better accuracy.
This thing looks amazing, and entire first batch is sold out!
Definitely going to pick one up when they are available. I might save a few bucks diong the DIY route, but at the end of the day, I would just buy 3-4 more shares of a vanguard thing, and have to tinker/maintain a grafana dashboard, where this thing is probably getting new apps/updates/features monthly.
Why every second word in this article is "AirGradient"? Most important/expensive sensor is from Senseair, controller from Wemos, etc. I've made same monitoring solution using same components following some years old tutorial and have never heard about "AirGradient".
Someone knows if living in a home with "bad" air quality is worse for someone's live than living under constant stress thank to air monitoring telling that the air quality is not perfect ?
Man I'd pay quite some $ for this to be plug -enter wifi-pw- and play with Home Assistant integration, all data stays in my LAN of course. Something with Tasmota or esphome? A touch of mqtt...
I think all of those sensors (as well as the OLED display) are supported by esphome. That'll give you near plug-and-play with HomeAssistant with just a little YAML.
What's with radon mentions here and at AirGradient pages? Where would that come from, is this a US thing? Reminds me of 'asbestos-free cereal' xkcd joke.
EDIT:
> Radon is the second leading cause of lung cancer in the United States. Nationally, the EPA estimates that about 21,000 people die each year from radon-related lung cancer. Only smoking causes more lung cancer deaths.
> The case is well-ventilated, and my only complaint is the natural convection causes very-slightly-warmed air from the WeMos D1 and CO2 sensor to pass over the temperature and humidity sensor on the top, meaning those readings are always a bit higher than ambient—at least in my office.
Heh, this. I keep the thermostat between 78-80°F during the summer months (which allows the A/C to run enough to keep humidity down below 50%), and between 68-72°F in the winter.
Here in South Texas I keep my house at 78° during the daytime in A/C season (that's typically March-November, plus some days the other months). If the ceiling fan's aren't on, and the air isn't moving around properly, it can easily get up to 82°. It's perfectly comfortable. (You acclimate to it)
Understand, the average high is in the mid to upper 90's and trying to get a home a/c to cover a 20+ temperature difference is difficult and significantly drives up the monthly power bill.
When I lived in the desert, 82° was comfortable for me. Generally, the humidity was below 10% (NWS reading, as most cheap consumer sensors are not precise below 10%). But even in monsoon season, when the humidity would spike, it was still fine.
I guess you get used to it. My wife never did, so when she came home from work she'd turn the temperature down to 78°.
It was in the upper 80s/lower 90s throughout July and August, when this data was likely collected. And relative humidity hit 80-90% every morning, averaging about 65% as it warmed up. It's sticky in summer. I live in Michigan, and even with a cool breeze from our magnificent freshwater lake, half an hour inland it's similarly hot and humid. I kept our house at 78 when we're home, 82 when it's just the dog, and 76 when company comes over. I think the air conditioner keeps humidity in the 40% range, though I'm reading this article because I lack a hygrometer/air quality sensor and don't really have hard numbers for that, only that humidity is significantly less indoors than out.
Also, he mentions that the orientation of the case causes convection off the ESP8266 to increase the air temperature by a couple degrees (Farenheit).
If you're one of the Silicon Valley HN readers looking to move to the wide open spaces and relaxed culture of the Midwest, do be aware that climate is a big deal; coastal California's perpetual mild climate is an aberration.
Maine is relatively dry. My house generally stays around 40-60% humidity year round except during the coldest parts of the winter, independent of the outdoors in both extremes.
Relative humidity is a function of air temperature. 50% humidity at 60F is relatively comfortable, but 50% humidity at 90F is much more uncomfortable. What is really happening is the dew point is closer to your ambient surface skin temp, so water has a harder time evaporating/starts to collect.
Since air holds more water at higher temps (and a lot more, 90F air can hold almost 3x as much as 60F air), just comparing humidities without considering temp doesn't say much.
- 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.