Naively searching for every lines of the bill of materials gives me around $300, with a handful of items being around $50 and everything else under $5. I'm sure a hobbyist could find the parts for cheaper, especially things like individuals connectors that I found for around $5. I've seen them go as low as $0.25 when bulk purchased.
Disclaimer: it's possible that some SKUs led me to the wrong products. I am not into electronics. I encourage you do to the same exercise before drawing conclusions.
Not to undermine the DIY aspect which could be fun, but it looks like you could buy an Atmotube for about half as much (if you take the research survey) — https://ukstore.atmotube.com/. Though it doesn't register noise levels.
They can also build you an Atmocube which can measure noise and a few other things for $200-$500 based on what I found online.
Not sure why it needs an acceleromete, gyro or gps, and the solar circuitry might not be required for all use cases.
Seems a bit over engineered, unless they were gearing towards a roving platform your could put on the back of your bike, or a balloon.
Anecdotal, but my Atmotube v1 did not last very long after I was only a little rough with it (tied to a backpack). I wonder if the solution brought here might be more sturdy / easier to repair in the context of developing nations.
Perhaps some industrious person (looks around room) could put together a BOM on a site like Mouser to make it a little easier to order many of the parts.
We at AirGradient maintain popular indoor and outdoor open source air quality monitoring projects [1] and gained quite a lot of experience on air quality measurement.
The hard part of these projects is not connecting electronic modules and get some air quality data out of it but to ensure that the data is accurate and this is where I have some questions. The success of these kind of projects stands and falls with the trust that people have in the data it generates.
1) The built uses the Sensirion SPS30 PM sensor. As per Sensirion assembly guideline the maximum allowed air flow around the sensor is one meter per second. This corresponds to 3.6 km/h or 2.2 m/h. A car normally travels a multitude of this speed. I did not see anywhere in the built instructions how they manage the airflow inside the enclosure to be within this limit. In my opinion detailed airflow simulations inside the enclosure are essential.
2) Temperature and humidity has strong impacts on the accuracy of PM measurements and it is important that these are accounted for. This is already a challenge for stationary low cost sensors but having this sensor mounted on the roof of a car will probably give a wide vaiety of different heat exposures. I did not see how this is accounted for.
3) I am not sure if there are large advantages with mobile sensors compared to a high density stationary network of low cost sensors. Air pollution, especially on roads fluctuates a lot with peak times. So a measurmenet taken at 8am at a busy junction might be quite different a few hours later. How long do you keep past measurements valid for a certain location?
I applaud all open source projects in this space and it looks like a lot of effort went into this project so it would be great if above concerns could be addressed/clarified from somebody in the team.
Yeah, the idea of mounting them on top of vehicle seemed a bit strange to me too, given how the particulate sensors work. Perhaps they could use the GPS and just sample for a bit when the vehicle has been stopped for a few seconds?
I didn't think of the temperature issue - that does seem like a tricky problem too...
Usual disclaimer that MIT's PR dept is really effective (I've stopped paying attention them because of so much hype), and there's quite a chasm between a proof of concept and a mass-market device.
That one was supercharged by the Media Lab's PR organ. But even without that assistance, the regular MIT "news" office is head and shoulders above its peers in making the trivial appear transformational and the outstanding appear...boring.
My favorite was a publicity piece about a new proof for the behavior of higher-order manifolds with some absurd justification as to why you should care, something like how it would revolutionize battery electrodes or something like that.
We built those and got them running one evening at a Meetup in Erlangen - looks like they had to switch to a temperature/humidity sensor that requires soldering the pins on, because the ones we used back then came ready to plug in, not a soldering iron in sight.
I can vouch for that. A friend built one of these and since it worked really well, so I and some others built five more last year. Make sure to put a piece of window screen over the openings of the tube to keep insects and spiders out. If you have enough dexterity, you can even hide the screen inside the opening of the tube to make it less unsightly.
These measurement devices have a limited lifetime and I think it is really the intake of dust and dirt that limits how long they can be used. That's why they're not running continously but for some seconds every few minutes (because flowing air will carry dust much more easily). If it's clogged up with dust or dirt, it really might be at end of life. I keep the electronics and sensor of mine in a closed box if I am not operating it.
This sounds highly implausible for anything other than very crude and not-very-useful measurements. Quantifying air pollution is a fairly hard problem, chemically speaking. The composition of particulate matter is highly diverse as it may arise from a wide variety of sources, i.e. agricultural, industrial, wildfires, diesel engines, etc. Just looking at the particulate PM2.5/PM10, broadly speaking there's the organic carbon fraction and the inorganic metal fraction. The former is highly complex, e.g.:
> "The considerably increased chromatographic resolution in GC×GC [gas chromatography] allows separation of many UCM [organic carbon] compounds while the TOFMS [mass spectrometer] supplies mass spectral data of all separated compounds. However, the data sets are getting enormously complex. In a typical PM2.5 sample from Augsburg more than 15,000 peaks can be detected... "
Some particulate matter may have a heavy metal fraction, some may not and that's also not easy to determine (but was a major factor in leaded gasoline pollution). Here's a sample of the kind of work that has to be done to get reliable measurements:
> "...using quadrupole inductively coupled plasma – mass spectrometry (q-ICP-MS). We report improved measurements of key aerosol elements including Al, V, Cr, Fe, Ni, Cu, and Zn in airborne coarse particulate matter (PM10)... This technique was used to determine the elemental composition of over 150 PM10 samples collected from an industrialized region in Houston, TX."
On top of that there's nitrogen oxides and PAN, ozone, etc. The only relatively inexpensive recent innovations seem to be the use of drones to collect samples for lab analysis (would have been useful in East Palestine).
Getting accurate measurements of all the species involved in air pollution requires a modern analytical lab packed with equipment that costs hundreds of thousands of dollars and highly trained technicians to operate. The press release and snippets from the paper don't address such important details at all.
Most definitely it's hard to dig into the actual composition of air pollution. But "how much PM2.5 is in the air", while definitely crude, is still extremely useful. That said, decent sensors for PM concentration are already pretty cheap (<$100 for a module; ~$100 for a full package), so unless the price is going way down it's unclear how useful this particular innovation is.
I spent some hours on Amazon and AliExpress looking at cheap (under 100 bucks) air quality devices, and all I found was junk that made up figures for most "measures", if you read carefully the buyer reviews.
I suppose the cheap & good device does not exist, but the junk seems to be selling fairly well. The demand is there, but not the product, and this press release seems another way of cashing in ...
Big Clive on YouTube has done some videos on devices like these - like a "CO₂ meter" that seemed to actually just contain a VOC sensor - while it was quite good at detecting things like alcohol vapour, it's just useless as an actual CO₂ sensor.
I wouldn't trust anything from AliExpress or anything that's not a known quality brand on Amazon. I'm looking at maybe getting a Davis Instruments AirLink to (at different times) do both indoor and outdoor monitoring for PM1, 2.5 and 10, as well as temperature and humidity, but it's pretty pricy (a bit over AU$300). There's also the new Ikea indoor monitoring device [1] coming out next month too, which should be a lot more affordable I think.
A lot of these cheap, portable sensors "cheat" in one way or another. E.g CO2 sensors that assume they'll be subject to open air once every few days, using that minimal CO2 value as a baseline. So while they give numbers which can be useful if the user is aware of its limitations, they're far from being analytical tools.
In contrast PM is pretty easy to get right. Shine laser, count particles.
Not only that, but they are deployed on top of automobiles, where the air quality in the surrounding air is going to be worse to begin with. I understand the benefits of using GPS, but I don't see where they mention this being an issue.
Hadn't heard of that but built something similar by adapting tutorials from adafruit for their microcontrollers, lcds, air quality sensors, starting with https://learn.adafruit.com/adafruit-trinkey-qt2040
I don’t know if this is the device to do it, but the premise is solid: create awareness that air pollution is a real thing affecting specific areas in which you are breathing right now, not just an abstract bad thing that may or may not be happening somewhere to someone.
I'm debating buying one for myself so I can judge whether air pollution is effecting my asthma. You can find AQI for a lot of cities but it appears the calculation often isn't done with local devices. Satellite imaging?
For home use, you should aim for multiple sensors that can track temperature, humidity, CO2, VOC, and PM2.5.
CO2 is important to track as high concentrations can impact sleep quality and critical thinking ability.
VOCs is important to track as they are associated with asthma and allergic reactions.
CO2 can only be removed by opening a window.
Most VOCs come from household chemicals and are only removed by using lots and lots of charcoal filters as the HEPA filters in household air purifiers aren't able to capture it in significant amounts.
Readit News
Link to assembly guide: https://github.com/MIT-Senseable-City-Lab/OSCS/blob/main/Bui...
Link to bill of materials: https://docs.google.com/spreadsheets/d/1-fR-0hTxHKbjaRf8DbH6...
Naively searching for every lines of the bill of materials gives me around $300, with a handful of items being around $50 and everything else under $5. I'm sure a hobbyist could find the parts for cheaper, especially things like individuals connectors that I found for around $5. I've seen them go as low as $0.25 when bulk purchased.
Disclaimer: it's possible that some SKUs led me to the wrong products. I am not into electronics. I encourage you do to the same exercise before drawing conclusions.
They can also build you an Atmocube which can measure noise and a few other things for $200-$500 based on what I found online.
Deleted Comment
https://doi.org/10.1016/j.atmosenv.2023.119692
The hard part of these projects is not connecting electronic modules and get some air quality data out of it but to ensure that the data is accurate and this is where I have some questions. The success of these kind of projects stands and falls with the trust that people have in the data it generates.
1) The built uses the Sensirion SPS30 PM sensor. As per Sensirion assembly guideline the maximum allowed air flow around the sensor is one meter per second. This corresponds to 3.6 km/h or 2.2 m/h. A car normally travels a multitude of this speed. I did not see anywhere in the built instructions how they manage the airflow inside the enclosure to be within this limit. In my opinion detailed airflow simulations inside the enclosure are essential.
2) Temperature and humidity has strong impacts on the accuracy of PM measurements and it is important that these are accounted for. This is already a challenge for stationary low cost sensors but having this sensor mounted on the roof of a car will probably give a wide vaiety of different heat exposures. I did not see how this is accounted for.
3) I am not sure if there are large advantages with mobile sensors compared to a high density stationary network of low cost sensors. Air pollution, especially on roads fluctuates a lot with peak times. So a measurmenet taken at 8am at a busy junction might be quite different a few hours later. How long do you keep past measurements valid for a certain location?
I applaud all open source projects in this space and it looks like a lot of effort went into this project so it would be great if above concerns could be addressed/clarified from somebody in the team.
[1] https://www.airgradient.com/open-airgradient/kits/
[2] https://sensirion.com/media/documents/7990F04A/616544B0/Sens...
I didn't think of the temperature issue - that does seem like a tricky problem too...
How do you guys accurately measure humidity electronically?
The Open Agriculture fraud is a living example: https://gizmodo.com/mit-built-a-theranos-for-plants-18379682...
My favorite was a publicity piece about a new proof for the behavior of higher-order manifolds with some absurd justification as to why you should care, something like how it would revolutionize battery electrodes or something like that.
PS: "living example" was a nice touch.
Data available at luftdaten.info
https://sensor.community/de/sensors/airrohr/
Not sure how to calibrate those. I didn't buy 3 of them to measure the accuracy.
> "The considerably increased chromatographic resolution in GC×GC [gas chromatography] allows separation of many UCM [organic carbon] compounds while the TOFMS [mass spectrometer] supplies mass spectral data of all separated compounds. However, the data sets are getting enormously complex. In a typical PM2.5 sample from Augsburg more than 15,000 peaks can be detected... "
https://www.sciencedirect.com/science/article/abs/pii/S00219...
Some particulate matter may have a heavy metal fraction, some may not and that's also not easy to determine (but was a major factor in leaded gasoline pollution). Here's a sample of the kind of work that has to be done to get reliable measurements:
> "...using quadrupole inductively coupled plasma – mass spectrometry (q-ICP-MS). We report improved measurements of key aerosol elements including Al, V, Cr, Fe, Ni, Cu, and Zn in airborne coarse particulate matter (PM10)... This technique was used to determine the elemental composition of over 150 PM10 samples collected from an industrialized region in Houston, TX."
https://www.sciencedirect.com/science/article/abs/pii/S00032...
On top of that there's nitrogen oxides and PAN, ozone, etc. The only relatively inexpensive recent innovations seem to be the use of drones to collect samples for lab analysis (would have been useful in East Palestine).
Getting accurate measurements of all the species involved in air pollution requires a modern analytical lab packed with equipment that costs hundreds of thousands of dollars and highly trained technicians to operate. The press release and snippets from the paper don't address such important details at all.
I suppose the cheap & good device does not exist, but the junk seems to be selling fairly well. The demand is there, but not the product, and this press release seems another way of cashing in ...
I wouldn't trust anything from AliExpress or anything that's not a known quality brand on Amazon. I'm looking at maybe getting a Davis Instruments AirLink to (at different times) do both indoor and outdoor monitoring for PM1, 2.5 and 10, as well as temperature and humidity, but it's pretty pricy (a bit over AU$300). There's also the new Ikea indoor monitoring device [1] coming out next month too, which should be a lot more affordable I think.
1. https://about.ikea.com/en/newsroom/2023/02/14/ikea-launches-...
In contrast PM is pretty easy to get right. Shine laser, count particles.
https://community.home-assistant.io/t/sniffer-air-quality-se...
https://github.com/kylemanna/sniffer
CO2 is important to track as high concentrations can impact sleep quality and critical thinking ability.
VOCs is important to track as they are associated with asthma and allergic reactions.
CO2 can only be removed by opening a window.
Most VOCs come from household chemicals and are only removed by using lots and lots of charcoal filters as the HEPA filters in household air purifiers aren't able to capture it in significant amounts.