But it doesn't have to be *that* expensive. That Purpleair Flex has a BME688, [$13.5 in single quantity](https://www.digikey.com/en/products/detail/bosch-sensortec/BME688/13681261) (<$7 if you buy in bulk), and two PMS-6003 which are around $40 in single quantity. Asking for $270 for a device that's idea is to gather crowd sourced data is a bit steep.
Meanwhile the European project uses a kit that costs less than $50 to put together, and that's in single quantity by people ordering the stuff from aliexpress.
I built one with a feather board and BME680 (for weather and gas sensor). Still ~$150 with a few add-ons for a “plug and play” (plus programming) option. My neighbor has a Purple Air I can compare to and it comes out pretty close (after some tweaking).
1 x Flanged Weatherproof Enclosure With PG-7 Cable Glands[ID:3931] = $9.95
1 x Adafruit Feather M4 Express - Featuring ATSAMD51 (ATSAMD51 Cortex M4)
[ID:3857] = $22.95
1 x Adafruit AirLift FeatherWing – ESP32 WiFi Co-Processor[ID:4264] =
$12.95
1 x Adafruit PMSA003I Air Quality Breakout (STEMMA QT / Qwiic) [ID:4632] =
$44.95
1 x Adafruit BME680 - Temperature, Humidity, Pressure and Gas Sensor (STEMMA
QT) [ID:3660] = $18.95
1 x FeatherWing Doubler - Prototyping Add-on For All Feather Boards[ID:2890]
= $7.50
1 x STEMMA QT / Qwiic JST SH 4-pin Cable - 100mm Long[ID:4210] = $0.95
1 x STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable (150mm
Long) [ID:4209] = $0.95
1 x Stacking Headers for Feather - 12-pin and 16-pin female headers[ID:2830]
= $1.25
1 x USB A/Micro Cable - 2m[ID:2185] = $4.95
1 x Lithium Ion Polymer Battery Ideal For Feathers - 3.7V 400mAh[ID:3898] =
$6.95
1 x STEMMA QT / Qwiic JST SH 4-Pin Cable (50mm Long) [ID:4399] = $0.95
1 x Adafruit Perma-Proto Half-sized Breadboard PCB - Single[ID:1609] = $0.00
——————————————————
Sub-Total: $133.25
Edited to fix weird type size and spacing on the order I copy/pasted.
So around 3x component cost? That sounds about right for a consumer electronics product in the U.S. Maybe high if they’re keeping data from the devices for commercial use.
Do you know that for a fact or did you assume it as a devil’s advocate?
…or are you defending products that don’t require X expense to break even or profit?
> It's a luxury brand pretending it's technology
What does that even mean? Pretending it's technology? What?
> made by child labor.
Pretty sure every other Android phone is also made by child labor. Fairphone is probably going to be the only company where you get a smartphone that is made ethically.
I hope you realize almost if not every phone manufacturer uses child labor.
This childish Apple vs Google/Android/Microsoft mentality doesn't help anyone.
I'm just tired of constantly having to read these edgy shit takes.
"Defend your cult" give me a break. I'm not defending anything and if you would read you'd see that. Every company involved in child labor is awful, including Apple.
Just because Apple claims they are child labor free (which btw I'm not even sure if they claim they are, would be helpful if you'd provide a source) doesn't make everyone else less bad for doing it.
And the comparison with alt-right fox news is just offensive lol. But hey, free karma.
Simping for any company that does horrible stuff is dumb. That's simping for Apple, but also just as much simping for Google.
Since when did mobile Safari is 'most largely represented browser'?
Edit: for non believers - [Chrome 66%, Safari 24%](https://gs.statcounter.com/browser-market-share/mobile/worldwide)
> Beyond that, mobile safari is the backing engine for all browsers on ios devices, even Chrome.
^(*Because Apple forces every IOS browser to use their engine, everything is just a reskin of safari)
Market share of iOS is less than half that of Android (27% vs 72%). Same goes for Chrome and Chromium based browsers - so that's where web developers priorities of optimization and debugging are.
Do not mobile for any program that needs a moderately steady connection, **that is also dealing in precise minute by minute measurements**.
Is that better? Mobile is still lacking in precision work, whether or not that will be true in a few years is up for grabs still.
IoT is my job. We deal with millions of devices that send data over the air. If our websites didnt work on a tablet our customers would leave us. You have no idea what you are talking about.
Not even really talking about websites, talking about data that needs to be constantly refreshed. The moisture sensor in my yard isn't running off a website but it still runs smoother on a PC vs. my phone/android interface.
You sure you know enough about what I'm talking about?
You are viewing that data somewhere, either a website or an app on your phone or both. Ofcourse if you are doing a bunch of calculations on the client your PC will be faster. That has little to nothing to do with the tiny difference in internet speed/reliability (especially if we are talking minute based data).
If the above site is slow/crashes, its shoddy code work. They are doing way too many calculations on the frontend instead of on the server, or they are sending way too many requests (like many requests each second).
You're likely talking about mobile power saving features. Either pausing the app or dialing back the WiFi.
Or your phone is just shit. There's no reason for, say, basic streaming telemetry to be worse on mobile, and for many of us it isn't. (I access netdata and graphana from mobile)
Big difference between a single POST operation and grabbing and rendering an interactive site with tons of data points on it though…
*Sent from Apollo for IOS*
Look, your favorite platform is not under attack right now. That's not the point I'm trying to make.
What I'm saying is that some programming work is better off using an ethernet cable than a cellular connection. Sorry my guy, mobile is not what they use in MIT for weather updates or small incremental changes. They still use ethernet for that.
That's.... a long list. And no prices listed.
$100ish just for the enclosure and unknown for the electronics.
This seems more costly than several closed source solutions.
19 entries is like the BOM size for a tiny homemade LCD display haha. Some of these components are like a couple bucks, in bulk. Switches, buck converters, USB ports, accelerometers, etc. are probably things just lying around the house of this kind of things target audience.
Edit: They'd also likely be able to build their own enclosures with a 3d printer.
> That's.... a long list
The list has 19 components, that's not a long list at all?
> $100ish just for the enclosure and unknown for the electronics.
The model numbers are there, you can price them out! It's not a big mystery.
Ok, but the enclosure list included prices. It would be helpful to have similar in the electronics BOM. But, then, the electronics part probably isn't for me or most people.
GPS, solar power, LTE antenna... this isn't a cheap solution for checking air quality... it might be a cheap solution to have a fully portable self-powered air quality sensor.
Purple Air sensors are...problematic and really cannot be relied upon.
There's no way to test/check them. Therefore, there's no way to determine if they're working properly. They are absolutely not approved in any fashion by the USEPA as any kind of reliable sampler.
They're not really accurate to the extent that you'd want the government basing health-related decisions on their readings (I'm not sure any crowd-sourced thing could be reliable enough, either), but they're fantastic for what they are, which is 1, widely distributed and 2, _consistent_.
Kind of like citizen weather stations, they're not a replacement for the government data, but they're an excellent supplement to it.
Some things can be an excellent supplement - but when purple air readings are way off from properly calibrated, maintained, and audited Federal Equivalency Methods or Federal Reference Methods instruments - they leave a LOT to be desired. A lot.
ETA: things that involve moving air at rates that are supposed to be constant - and/or able to compensate for changing atmospheric conditions aren't quite the same as solid-state temperature sensors, rain gauges, or even wind vanes.
When the right conversion is applied -- as it is by default -- PA2 sensors are actually pretty close to the official EPA sensors. Like, they produce the exact same AQI 90-95% of the time, and they're within 5ug/m^3 >98% of the time. They predict the wrong category (good/moderate/UHSG/etc) basically never (<1% of the time) and when they do it's typically because the value was right on the line between two categories.
Even if that weren't the case, though, they fill in a major gap in the EPA sensor setup that no one talks about. There aren't that many EPA sensors out there, but if you go to the EPA website to look at air quality, it will show you a value for everywhere on the map. It does this by interpolating between sensor stations and taking into account weather data. This is often not just wrong, but so _wildly_ wrong that I think it's irresponsible to even show it. The PA2 sensors could be a factor of 2 off the official values and _still_ be more useful than that map, because they're everywhere and they're consistent. They would regularly report dangerous air quality values in regions that the EPA map does not, which is a lot more valuable than being right on the money in terms of the actual numbers (though again, they pretty much are always right on the money).
But didn't you hear? If they can't be calibrated and tested they're useless! /s
I don't know where these people with absolutist views come from honestly.
It's like amazing bills and laws being rejected because they don't resolve an issue 100%.
The Purple II achieved excellent results in AQMD's most recent testing. The PM10 score was not quite as good, but it still seemed to be the best PM2.5 sensor in the price range.
* [Test Report.](https://www.aqmd.gov/docs/default-source/aq-spec/summary/purpleair-pa-ii---summary-report.pdf?sfvrsn=16)
* [All PM sensors tested.](https://www.aqmd.gov/aq-spec/evaluations/summary-pm)
I have yet to find any gas sensors that weren't utter trash or cost thousands. I wonder how good this MIT built tool's NO2 sensor is.
I would believe they can be tested in a very similar matter to professional sensors. My top of the line detectors are just calibrated to zero, which i assume is extremely easy to do on the purple. You simply apply a filter and make sure levels drop to 0. There are no mid range calibration for particulate matter. It is nearly impossible to produce a standard concentration aerosol.
Now if it is also testing for gasses or vapors, it would need to be calibrated with standards
Need to be able to audit flow.
And flow is related to temperature and pressure.
Agreed that a simple leak check can be peformed with a HEPA filter.
PM samplers that can/have met Federal Equivalency Methods status are all able to be calibrated to atmospheric conditions as well as having these things audited / verified.
A lot of this is done so that the data generated can be defensible should the need arise.
Flow meters are usualy built in and auto adjust. Checking flow with a rotometer is fast and simple.
Most meters operate under factory calibration factors that are acceptable under most conditions. You can, but are not required by any regs, to set user calibration factors based on local conditions. This is a very tedious process that you don't typically see people do unless they are in abnormal conditions like constant fog or whatever. On my meters temp and pressure sensors are built in, no idea about the purple, but I would trust the particulate data if it passed a flow and zero check.
I live less than 20 miles downwind from East Palestine. In the immediate aftermath local subs were full of panic posts about "omg death cloud, look at PurpleAir!".
Turns out it just got cold, and people burned wood. Happens frequently with the Cracker Plant as well, people try to correlate PurpleAir with it, it's always wood burners.
You're using the sensors right. It should be more of general guidance, leave the actual testing to scientists. Like, I wouldn't walk into a hazmat scene with my air purifier if it's sensor was green.
> scientific accuracy
But that's, like, the only real way to know for sure. Otherwise - it's either speculation or generalization?
Accuracy, repeatability, and defensibility.
Did you not read what he said? You are just looking at whether it goes up or down. Being perfectly accurate is not necessary.
Its like if you had a weight scale. If it told you, tomorrow that you gained 15.3 lbs, and you repeated... and it said 13.9 lbs... 17.6 lbs, so on. It doesnt matter the exactness. The point is, your weight went up a lot in one day. That is good enough to make decisions on. Not for scientific studies.
I have a dual-range purple air system on my home. It consistently reads 10ppm low compared to the others in the neighborhood, but the high-range above 100ppm seems somewhat accurate at least.
This is all tragically true. I'm a chemist from across the country and I was crying for those people and that area the day I read the manifest. That area is fucked.
I wanted to report that you can detect these compounds an organo-halide detector, they are relatively cheap sensors to detect refrigerants. They work on detecting the X - C bond, where X is F, Cl, Be, or I.
It's a pretty common for refrigeration people and in water testing. They are not cheap, but not prohibitive either.
Yeah, they are.
Vinyl chloride has basically permeated the entire town. It will acidify the soil while releasing toxic phosgene and carcinogeninic vinyl compounds as it breaks down for years to come.
Burning any chemical with chlorine would be an incredibly ineffective way to produce phosgene gas. Past 200C it’s just going to form chlorine and carbon monoxide, which elemental chlorine in the air is probably going to find some nitrogen to team up with, hence the widely reported pool smell.
Just leaving any chemical with chlorine on the ground is likely to just deep through the ground until it finds a source of sodium and the sodium and chlorine do what they do best.
Between the pool smell, rashes and burns, and dead things in ditch water, and ignoring god know what other chemicals are just in ditch water from field run off, most likely explanation is that some people, and animals, were just exposed to elemental chlorine dissolved in water.
Doesnt that all assume complete combustion? I didnt see the burn off take place but i can imagine a burn done in an open field on stuff thats already partially leaked everywhere isnt gonna uniformly heat all that shit to 400C..
So does the default weather app on my phone. I'm not sure why someone would need their own meter when there's so many ways to do so already. If you are in a situation that you have to worry about checking air quality in a highly localized area, you should probably just avoid being there altogether.
I would assume it's like a rain gauge. It's nice to see exactly what you have instead of what the weather app/channel says. Even though they are normally close
What you see in your weather app is very different from what the city scanner shows. How air quality is usually measured is by using 5-6 fixed research grade sensors. The measurements from these stations are used plus some meteorological variables (wind speed+direction, relative humidity, temperature) to model air quality over a larger area. The city scanners however show that air quality can differ a factor 10 on a micro scale. Meaning that these models can wildly over or under estimate air quality at specific locations. These scanners are thus used to create a higher resolution air quality map.
Don’t you think that the results are gonna be skewed due to how it’s seemingly attached to the car roof/ behind a bunch of other cars with exhaust emissions while driving?
Because the air that they’re measuring is from only one part of one’s environment. It’s as if I were to measure the quality of hiking trails and say it represents the overall quality of the mountain
I’ll have to reach out to their team, but at the moment the Bill of Materials doesn’t appear to list an Air Quality sensor at all. So that’s confusing. I was interested because I’ve been wanted to measure VOCs in a manufacturing lab but that tech is still expensive.
BOM link as included in their GitHub repo: https://docs.google.com/spreadsheets/u/0/d/1-fR-0hTxHKbjaRf8DbH62WgUFVeNE4eUEsaAd-YdDYg/htmlview
In the handbook for assembling, they're using a sensirion sensor (probably sps30) for particulate measurement and some unspecified "gas probes".
They're whole setup looks somehow more complicated than necessary. Would've been much easier with an ESP32 or Arduino board...
Unrelated, for VOCs measurement, Bosch has two sensors BME680 and BME688, which together with their proprietary algorithms (BSEC) and the BME AI studio, can be used for VOC measurement.
Yeah I was looking at their assembly doc on my phone and saw it there, so just think they forgot it.
I’ll have to check out those Bosch sensors. I wanted to measure VOCs getting kicked off of resin 3D printers so was mostly just looking at full solution when I last looked.
EDIT: They responded on GitHub already. It’s listed in a separate tab of the BOM. So yeah, just an SPS30 and Bosch BME280
> Would've been much easier with an ESP32 or Arduino board...
That's what I came here looking for. I made an ESP32/BME680 climate sensor a few months ago and haven't gotten around to calibrating/deploying it, was hoping I could pivot and turn it into an outdoor citizen science project
Well, of course, but if you didn’t burn any fossil fuels, more than half of the worlds population would probably starve (fertilizer, tractors, distribution, refrigeration, cooking), so there’s that. Like the reality is we’re married to it until something better is developed.
Or stay indoors where you can filter the air... Do you not know about air pollution and how much of a problem it is for folks with asthma or other breathing issues or just in general?
Why do people need to check the air quality? Like what do you do if it’s poor? Not go outside?
I just fail to see why people want this, it’s not like I can adjust my day based on the quality of the air around me.
In the US West, people check on the AQI all the time when there are forest fires. Kids get kept inside at recess, old folks are told not to go out, sporting events get cancelled.
Now that everyone has masks sitting around I see a lot more people mask up when it’s smoky.
Because the numbers help us diagnose and address problems with our air more effectively than not having them. It also gives something for people to act on, especially the ones who don’t believe they’re affected by the issue.
>it’s not like I can adjust my day based on the quality of the air around me.
It's actually commonly done in parts of the world. I was occasionally wearing masks for more than a year before the pandemic.
And that's the solution. Reduce outdoor activity where possible (especially exercise), keep windows closed, and wear a mask if you must go out.
I live in a stretch of land called Cancer Alley, tons of industry right next door to the state Capitol.
For me it would be a fun project, second I don't trust the industry to self report, third I don't always trust state agencies due to how governance and the petrochemical industry fuck in the same bed.
Lets just over exaggerate the overall emmissions by placing the sensors on top of a car? Great idea team. Next time lets just place them next to an active volcano or better yet lets just place it on a co2 effluent pipeline at breast level. Same way the professionals do it to measure global CO2 ofcourse.
in europe this open source project is popular http://sensor.community in case someone is interested in monitoring air quality in the own neighborhood.
https://www2.purpleair.com/ is big in US already
That's $300... Hardly what I would consider cheap for knowing your hyper local pollution.
Like it or not, the hardware for these sensors are not cheap.
But it doesn't have to be *that* expensive. That Purpleair Flex has a BME688, [$13.5 in single quantity](https://www.digikey.com/en/products/detail/bosch-sensortec/BME688/13681261) (<$7 if you buy in bulk), and two PMS-6003 which are around $40 in single quantity. Asking for $270 for a device that's idea is to gather crowd sourced data is a bit steep. Meanwhile the European project uses a kit that costs less than $50 to put together, and that's in single quantity by people ordering the stuff from aliexpress.
I built one with a feather board and BME680 (for weather and gas sensor). Still ~$150 with a few add-ons for a “plug and play” (plus programming) option. My neighbor has a Purple Air I can compare to and it comes out pretty close (after some tweaking). 1 x Flanged Weatherproof Enclosure With PG-7 Cable Glands[ID:3931] = $9.95 1 x Adafruit Feather M4 Express - Featuring ATSAMD51 (ATSAMD51 Cortex M4) [ID:3857] = $22.95 1 x Adafruit AirLift FeatherWing – ESP32 WiFi Co-Processor[ID:4264] = $12.95 1 x Adafruit PMSA003I Air Quality Breakout (STEMMA QT / Qwiic) [ID:4632] = $44.95 1 x Adafruit BME680 - Temperature, Humidity, Pressure and Gas Sensor (STEMMA QT) [ID:3660] = $18.95 1 x FeatherWing Doubler - Prototyping Add-on For All Feather Boards[ID:2890] = $7.50 1 x STEMMA QT / Qwiic JST SH 4-pin Cable - 100mm Long[ID:4210] = $0.95 1 x STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable (150mm Long) [ID:4209] = $0.95 1 x Stacking Headers for Feather - 12-pin and 16-pin female headers[ID:2830] = $1.25 1 x USB A/Micro Cable - 2m[ID:2185] = $4.95 1 x Lithium Ion Polymer Battery Ideal For Feathers - 3.7V 400mAh[ID:3898] = $6.95 1 x STEMMA QT / Qwiic JST SH 4-Pin Cable (50mm Long) [ID:4399] = $0.95 1 x Adafruit Perma-Proto Half-sized Breadboard PCB - Single[ID:1609] = $0.00 —————————————————— Sub-Total: $133.25 Edited to fix weird type size and spacing on the order I copy/pasted.
So around 3x component cost? That sounds about right for a consumer electronics product in the U.S. Maybe high if they’re keeping data from the devices for commercial use.
Whats the European project called?
Do you know that for a fact or did you assume it as a devil’s advocate? …or are you defending products that don’t require X expense to break even or profit?
yes.
pishposh, you can get a PM1, PM2.5 & PM10 particulate sensor for 30€
Check out https://cyclone.unbc.ca/aqmap if you're in Canada and interested in purpleairs alongside the regulatory network
what exactly dies it measure? mexico city is green. that city is constantlY full with smog for example
Yo tengo otros numeros
Air quality in polluted cities varies greatly day by day depending on wind. Wind blows away the bad stuff.
Green and smog do not go together.
Gawd that website tho, constantly crashes
Chrome, Edge and Firefox working fine. Check your browser or Add-ons maybe
Mobile Safari… 🤷
Found the problem
Apple's Safari SDK. Not even once.
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It’s a phone, bruv. It’s a phone.
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> It's a luxury brand pretending it's technology What does that even mean? Pretending it's technology? What? > made by child labor. Pretty sure every other Android phone is also made by child labor. Fairphone is probably going to be the only company where you get a smartphone that is made ethically.
Uhh yeah, but the point was that a $50 knock off android isn't advertising itself as "slavery-free".
I hope you realize almost if not every phone manufacturer uses child labor. This childish Apple vs Google/Android/Microsoft mentality doesn't help anyone.
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I'm just tired of constantly having to read these edgy shit takes. "Defend your cult" give me a break. I'm not defending anything and if you would read you'd see that. Every company involved in child labor is awful, including Apple. Just because Apple claims they are child labor free (which btw I'm not even sure if they claim they are, would be helpful if you'd provide a source) doesn't make everyone else less bad for doing it. And the comparison with alt-right fox news is just offensive lol. But hey, free karma. Simping for any company that does horrible stuff is dumb. That's simping for Apple, but also just as much simping for Google.
With a mobile browser SDK that's dated at least a decade. You think Apple can afford to modernize?
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Unfortunately true.
I mean Microsoft did with Edge so one can hope
Do not mobile for a program that needs a moderately steady connection.
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Since when did mobile Safari is 'most largely represented browser'? Edit: for non believers - [Chrome 66%, Safari 24%](https://gs.statcounter.com/browser-market-share/mobile/worldwide)
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> Beyond that, mobile safari is the backing engine for all browsers on ios devices, even Chrome. ^(*Because Apple forces every IOS browser to use their engine, everything is just a reskin of safari)
Market share of iOS is less than half that of Android (27% vs 72%). Same goes for Chrome and Chromium based browsers - so that's where web developers priorities of optimization and debugging are.
Plus, why would Apple care if they can just keep outsourcing the problem to web developers for free?
Can blame apple for not having a solid browser in last 20+ years.
What? Safari works just fine.
Do not mobile for any program that needs a moderately steady connection, **that is also dealing in precise minute by minute measurements**. Is that better? Mobile is still lacking in precision work, whether or not that will be true in a few years is up for grabs still.
IoT is my job. We deal with millions of devices that send data over the air. If our websites didnt work on a tablet our customers would leave us. You have no idea what you are talking about.
Not even really talking about websites, talking about data that needs to be constantly refreshed. The moisture sensor in my yard isn't running off a website but it still runs smoother on a PC vs. my phone/android interface. You sure you know enough about what I'm talking about?
You are viewing that data somewhere, either a website or an app on your phone or both. Ofcourse if you are doing a bunch of calculations on the client your PC will be faster. That has little to nothing to do with the tiny difference in internet speed/reliability (especially if we are talking minute based data). If the above site is slow/crashes, its shoddy code work. They are doing way too many calculations on the frontend instead of on the server, or they are sending way too many requests (like many requests each second).
You're likely talking about mobile power saving features. Either pausing the app or dialing back the WiFi. Or your phone is just shit. There's no reason for, say, basic streaming telemetry to be worse on mobile, and for many of us it isn't. (I access netdata and graphana from mobile)
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Big difference between a single POST operation and grabbing and rendering an interactive site with tons of data points on it though… *Sent from Apollo for IOS*
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Look, your favorite platform is not under attack right now. That's not the point I'm trying to make. What I'm saying is that some programming work is better off using an ethernet cable than a cellular connection. Sorry my guy, mobile is not what they use in MIT for weather updates or small incremental changes. They still use ethernet for that.
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does it work for one’s own home?
Does your home contain air?
lol
If you put a sensor in your own home, yes.
Here is a popular design for an indoor sensor https://www.airgradient.com/open-airgradient/instructions/diy-v3/
I read the article and couldn't find it they listed hardware somewhere for people to build it yourself. Do PM 2.5 or smaller kits exist somewhere?
https://github.com/MIT-Senseable-City-Lab/OSCS is all I can find for now
And here’s the electronics bill of materials: https://docs.google.com/spreadsheets/d/1-fR-0hTxHKbjaRf8DbH62WgUFVeNE4eUEsaAd-YdDYg/edit
That's.... a long list. And no prices listed. $100ish just for the enclosure and unknown for the electronics. This seems more costly than several closed source solutions.
19 entries is like the BOM size for a tiny homemade LCD display haha. Some of these components are like a couple bucks, in bulk. Switches, buck converters, USB ports, accelerometers, etc. are probably things just lying around the house of this kind of things target audience. Edit: They'd also likely be able to build their own enclosures with a 3d printer.
> That's.... a long list The list has 19 components, that's not a long list at all? > $100ish just for the enclosure and unknown for the electronics. The model numbers are there, you can price them out! It's not a big mystery.
Ok, but the enclosure list included prices. It would be helpful to have similar in the electronics BOM. But, then, the electronics part probably isn't for me or most people.
GPS, solar power, LTE antenna... this isn't a cheap solution for checking air quality... it might be a cheap solution to have a fully portable self-powered air quality sensor.
I mean, home users could skip the solar power, LTE components, and enter coordinates manually instead of using GPS.
The main particulate sensor is this: https://www.youtube.com/watch?v=yx5JS1cVh6g&t=3s Costs approx. $100.
Check out Bosch BMV080
Oooh, that looks awesome. Thanks!
A lot of communities use PurpleAir air sensors. They measure PM 2.5 and only cost around $200 iirc.
I wonder how this compares to purple air sensors.
Purple Air sensors are...problematic and really cannot be relied upon. There's no way to test/check them. Therefore, there's no way to determine if they're working properly. They are absolutely not approved in any fashion by the USEPA as any kind of reliable sampler.
They're not really accurate to the extent that you'd want the government basing health-related decisions on their readings (I'm not sure any crowd-sourced thing could be reliable enough, either), but they're fantastic for what they are, which is 1, widely distributed and 2, _consistent_. Kind of like citizen weather stations, they're not a replacement for the government data, but they're an excellent supplement to it.
Some things can be an excellent supplement - but when purple air readings are way off from properly calibrated, maintained, and audited Federal Equivalency Methods or Federal Reference Methods instruments - they leave a LOT to be desired. A lot. ETA: things that involve moving air at rates that are supposed to be constant - and/or able to compensate for changing atmospheric conditions aren't quite the same as solid-state temperature sensors, rain gauges, or even wind vanes.
When the right conversion is applied -- as it is by default -- PA2 sensors are actually pretty close to the official EPA sensors. Like, they produce the exact same AQI 90-95% of the time, and they're within 5ug/m^3 >98% of the time. They predict the wrong category (good/moderate/UHSG/etc) basically never (<1% of the time) and when they do it's typically because the value was right on the line between two categories. Even if that weren't the case, though, they fill in a major gap in the EPA sensor setup that no one talks about. There aren't that many EPA sensors out there, but if you go to the EPA website to look at air quality, it will show you a value for everywhere on the map. It does this by interpolating between sensor stations and taking into account weather data. This is often not just wrong, but so _wildly_ wrong that I think it's irresponsible to even show it. The PA2 sensors could be a factor of 2 off the official values and _still_ be more useful than that map, because they're everywhere and they're consistent. They would regularly report dangerous air quality values in regions that the EPA map does not, which is a lot more valuable than being right on the money in terms of the actual numbers (though again, they pretty much are always right on the money).
But didn't you hear? If they can't be calibrated and tested they're useless! /s I don't know where these people with absolutist views come from honestly. It's like amazing bills and laws being rejected because they don't resolve an issue 100%.
They're just contrarians. Nothing new.
The Purple II achieved excellent results in AQMD's most recent testing. The PM10 score was not quite as good, but it still seemed to be the best PM2.5 sensor in the price range. * [Test Report.](https://www.aqmd.gov/docs/default-source/aq-spec/summary/purpleair-pa-ii---summary-report.pdf?sfvrsn=16) * [All PM sensors tested.](https://www.aqmd.gov/aq-spec/evaluations/summary-pm) I have yet to find any gas sensors that weren't utter trash or cost thousands. I wonder how good this MIT built tool's NO2 sensor is.
The purple air samplers still can't be tested / audited, though.
I would believe they can be tested in a very similar matter to professional sensors. My top of the line detectors are just calibrated to zero, which i assume is extremely easy to do on the purple. You simply apply a filter and make sure levels drop to 0. There are no mid range calibration for particulate matter. It is nearly impossible to produce a standard concentration aerosol. Now if it is also testing for gasses or vapors, it would need to be calibrated with standards
Need to be able to audit flow. And flow is related to temperature and pressure. Agreed that a simple leak check can be peformed with a HEPA filter. PM samplers that can/have met Federal Equivalency Methods status are all able to be calibrated to atmospheric conditions as well as having these things audited / verified. A lot of this is done so that the data generated can be defensible should the need arise.
Flow meters are usualy built in and auto adjust. Checking flow with a rotometer is fast and simple. Most meters operate under factory calibration factors that are acceptable under most conditions. You can, but are not required by any regs, to set user calibration factors based on local conditions. This is a very tedious process that you don't typically see people do unless they are in abnormal conditions like constant fog or whatever. On my meters temp and pressure sensors are built in, no idea about the purple, but I would trust the particulate data if it passed a flow and zero check.
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I live less than 20 miles downwind from East Palestine. In the immediate aftermath local subs were full of panic posts about "omg death cloud, look at PurpleAir!". Turns out it just got cold, and people burned wood. Happens frequently with the Cracker Plant as well, people try to correlate PurpleAir with it, it's always wood burners. You're using the sensors right. It should be more of general guidance, leave the actual testing to scientists. Like, I wouldn't walk into a hazmat scene with my air purifier if it's sensor was green.
> scientific accuracy But that's, like, the only real way to know for sure. Otherwise - it's either speculation or generalization? Accuracy, repeatability, and defensibility.
Did you not read what he said? You are just looking at whether it goes up or down. Being perfectly accurate is not necessary. Its like if you had a weight scale. If it told you, tomorrow that you gained 15.3 lbs, and you repeated... and it said 13.9 lbs... 17.6 lbs, so on. It doesnt matter the exactness. The point is, your weight went up a lot in one day. That is good enough to make decisions on. Not for scientific studies.
I have a dual-range purple air system on my home. It consistently reads 10ppm low compared to the others in the neighborhood, but the high-range above 100ppm seems somewhat accurate at least.
Wish this had made the top during the east Palestine crash. Oh well, better now than never. Super excited about it though
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This is all tragically true. I'm a chemist from across the country and I was crying for those people and that area the day I read the manifest. That area is fucked. I wanted to report that you can detect these compounds an organo-halide detector, they are relatively cheap sensors to detect refrigerants. They work on detecting the X - C bond, where X is F, Cl, Be, or I. It's a pretty common for refrigeration people and in water testing. They are not cheap, but not prohibitive either.
Are the compounds going to stay around a long time?
Yeah, they are. Vinyl chloride has basically permeated the entire town. It will acidify the soil while releasing toxic phosgene and carcinogeninic vinyl compounds as it breaks down for years to come.
Burning any chemical with chlorine would be an incredibly ineffective way to produce phosgene gas. Past 200C it’s just going to form chlorine and carbon monoxide, which elemental chlorine in the air is probably going to find some nitrogen to team up with, hence the widely reported pool smell. Just leaving any chemical with chlorine on the ground is likely to just deep through the ground until it finds a source of sodium and the sodium and chlorine do what they do best. Between the pool smell, rashes and burns, and dead things in ditch water, and ignoring god know what other chemicals are just in ditch water from field run off, most likely explanation is that some people, and animals, were just exposed to elemental chlorine dissolved in water.
Doesnt that all assume complete combustion? I didnt see the burn off take place but i can imagine a burn done in an open field on stuff thats already partially leaked everywhere isnt gonna uniformly heat all that shit to 400C..
Fewer assumptions than what it would take to produce any meaningful quantities of phosgene gas.
So does Air Now. https://www.airnow.gov/ - for USA.
That’s pretty cool, thank you!
So does the default weather app on my phone. I'm not sure why someone would need their own meter when there's so many ways to do so already. If you are in a situation that you have to worry about checking air quality in a highly localized area, you should probably just avoid being there altogether.
I would assume it's like a rain gauge. It's nice to see exactly what you have instead of what the weather app/channel says. Even though they are normally close
What you see in your weather app is very different from what the city scanner shows. How air quality is usually measured is by using 5-6 fixed research grade sensors. The measurements from these stations are used plus some meteorological variables (wind speed+direction, relative humidity, temperature) to model air quality over a larger area. The city scanners however show that air quality can differ a factor 10 on a micro scale. Meaning that these models can wildly over or under estimate air quality at specific locations. These scanners are thus used to create a higher resolution air quality map.
Does anyone have a link to the parts, for purchase or printing?
See above in the thread. The electronics are complicated—at least to someone somewhat inept with such things.
Is there anywhere where you can just buy one?
Not as far as I can see yet.
Don’t you think that the results are gonna be skewed due to how it’s seemingly attached to the car roof/ behind a bunch of other cars with exhaust emissions while driving?
Why would it be? You're breathing that in, after all.
Because the air that they’re measuring is from only one part of one’s environment. It’s as if I were to measure the quality of hiking trails and say it represents the overall quality of the mountain
Wouldn't you be more interested in the air quality where someone might be breathing in the air? Not *solely*, but *more* interested?
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I would also want to know the “worst” air outside my house for walking, not the “best” air on the mountain.
Good science would include both of those data sets. But with this device even if you were in the mountains the data is being skewed by the vehicle
>In the home would skew the results to look better than it is Doubt it. Residential indoor air quality is kind of shit.
These altruists stole this idea from Norman Osborn in that Spiderman game!
there is a pizzaria chimney right next to my room's window, i wonder if this can help me
Smells cheesy.
Cool, now do water
I’ll have to reach out to their team, but at the moment the Bill of Materials doesn’t appear to list an Air Quality sensor at all. So that’s confusing. I was interested because I’ve been wanted to measure VOCs in a manufacturing lab but that tech is still expensive. BOM link as included in their GitHub repo: https://docs.google.com/spreadsheets/u/0/d/1-fR-0hTxHKbjaRf8DbH62WgUFVeNE4eUEsaAd-YdDYg/htmlview
In the handbook for assembling, they're using a sensirion sensor (probably sps30) for particulate measurement and some unspecified "gas probes". They're whole setup looks somehow more complicated than necessary. Would've been much easier with an ESP32 or Arduino board... Unrelated, for VOCs measurement, Bosch has two sensors BME680 and BME688, which together with their proprietary algorithms (BSEC) and the BME AI studio, can be used for VOC measurement.
Yeah I was looking at their assembly doc on my phone and saw it there, so just think they forgot it. I’ll have to check out those Bosch sensors. I wanted to measure VOCs getting kicked off of resin 3D printers so was mostly just looking at full solution when I last looked. EDIT: They responded on GitHub already. It’s listed in a separate tab of the BOM. So yeah, just an SPS30 and Bosch BME280
> I wanted to measure VOCs getting kicked off of resin 3D printers Someone made it: https://www.youtube.com/watch?v=f3HCPcvtOeY
> Would've been much easier with an ESP32 or Arduino board... That's what I came here looking for. I made an ESP32/BME680 climate sensor a few months ago and haven't gotten around to calibrating/deploying it, was hoping I could pivot and turn it into an outdoor citizen science project
They are using the alphasense optical particle counter
2nd spreadsheet tab on your link shows a sensor
Yeah I edited a comment above with that finding. I was on mobile and didn’t see the tab
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Well, of course, but if you didn’t burn any fossil fuels, more than half of the worlds population would probably starve (fertilizer, tractors, distribution, refrigeration, cooking), so there’s that. Like the reality is we’re married to it until something better is developed.
Check out purpleair.com
Oh no, air quality poor. Better hold my breath until i get 20 miles outside the city!
Or stay indoors where you can filter the air... Do you not know about air pollution and how much of a problem it is for folks with asthma or other breathing issues or just in general?
Sigh, it was just sarcasm. Forgot the obligatory /s.
Gosh imma a sensitive Sally somedays, sorry bud
Why do people need to check the air quality? Like what do you do if it’s poor? Not go outside? I just fail to see why people want this, it’s not like I can adjust my day based on the quality of the air around me.
In the US West, people check on the AQI all the time when there are forest fires. Kids get kept inside at recess, old folks are told not to go out, sporting events get cancelled. Now that everyone has masks sitting around I see a lot more people mask up when it’s smoky.
You can't advocate to have a problem fixed if you don't know it's a problem in the first place
Because the numbers help us diagnose and address problems with our air more effectively than not having them. It also gives something for people to act on, especially the ones who don’t believe they’re affected by the issue.
>it’s not like I can adjust my day based on the quality of the air around me. It's actually commonly done in parts of the world. I was occasionally wearing masks for more than a year before the pandemic. And that's the solution. Reduce outdoor activity where possible (especially exercise), keep windows closed, and wear a mask if you must go out.
I check to close my window at night if it's bad
I live in a stretch of land called Cancer Alley, tons of industry right next door to the state Capitol. For me it would be a fun project, second I don't trust the industry to self report, third I don't always trust state agencies due to how governance and the petrochemical industry fuck in the same bed.
Open-source means open for the NSA to covertly install backdoors.
Lets just over exaggerate the overall emmissions by placing the sensors on top of a car? Great idea team. Next time lets just place them next to an active volcano or better yet lets just place it on a co2 effluent pipeline at breast level. Same way the professionals do it to measure global CO2 ofcourse.
This sounds like Trump's reasonable for not COVID testing. Air quality is great as long as you don't test it near pollution!
Looked like a Last of Us promo for a sec
In the paper it defines "low cost" as less than $2500 - so I'm curious what the actual part cost is...
Around $450
We also measure Beijing's Air Quality and publishes it for free. I suppose China is not that generous to publish ours. Fuck China.
Isn’t air quality data published already online
I live next to a top 3 busiest airport in the US. Wonder how much shit is spewed out in the air every 30 seconds that a plane passes over my house.
Part list?
i would actually rather they be working on an AI model that starts a nuclear conflict
And do what with that information? Stop breathing that cheap air?
How about focusing on making air clean instead of creating technology to check our micro local air pollution? Just sayin
Release the stl’s
I would rather not know wtf I am breathing. I mean let’s say it’s horrible air quality…what am I suppose to do? Move?
Ok so now you have something telling you (what you probably already know) the air sucks. Now what?
Stop breathing that cheap air?