Low-cost open source device can measure air pollution anywhere
news.mit.edu
news.mit.edu
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.
Or a car, like the Flatburn device in the linked article?
$10: https://www.ikea.com/us/en/p/vindriktning-air-quality-sensor...
presumably not quite feature-comparable, but the article and website are rather absent in report what exactly the "flatburn" is detecting - sounds like "fine particulate" (PM2.5? PM10?) and NO2
they are that different
Or if you're building yourself, $35: https://sensirion.com/products/catalog/SEN55
Both include NO sensors.
Have you experience playing with it?
In particular, I wonder how usable it is with e.g. a Linux laptop.
It looks like the device uses a I2C interface.
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...
How do you guys accurately measure humidity electronically?
I didn't think of the temperature issue - that does seem like a tricky problem too...
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
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.
In contrast PM is pretty easy to get right. Shine laser, count particles.
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-...
https://community.home-assistant.io/t/sniffer-air-quality-se...
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.
This lists a "particle module", a temperature sensor and some other seemingly irrelevant sensors (GPS, accelerometer).
[1] https://github.com/MIT-Senseable-City-Lab/OSCS/tree/main/Bui...
edit: looks like the "particle module" is just a LTE/BT communication module, so really there don't seem to be any environmental sensors other than for temperature.
https://style.oversubstance.net/2021/08/diy-use-an-ikea-vind...
and of course previously on HN, airgradient DIY
https://news.ycombinator.com/item?id=27124671
The more the better. Maybe one day built into every smoke detector.
Maybe in a decade built into your phone. Another decade in your watch.
Been geeking out on AQ (air quality) lately and it’s fascinating. Market is very messy though. Few options with huge price discrepancies. Ultimately it looks like the sensors inside the fancy $300+ monitors cost a few dollars to acquire.
NO levels need to be collected alongside PM2 and CO/CO2. That stuff is really bad for you.
Insane amounts of inner-city schools without Air conditioning depend on open windows, kids sitting inside all-day next to busy streetscapes with diesel trucks roaring by. We know what this does to people.
The surburbian schools I went to as a kid didn't have air conditioning, just a line of windows in the back of the room that were always open during the spring & summer, and a line of windows in the front near the ceiling, that were also open on hot days.
AFAIK most of those schools were remodeled in the 2000s. They added air conditioning and nobody opens the windows anymore. That's great on a hot day, but man I really liked the fresh air on days with nice weather.
I get that "fresh air is best" and we kind-of also got that in covid times, its important to replace the air in a closed space. I like fresh air too. The problem is, what "fresh" is.
If you sit at a window above the garbage bins, for the first 10-20 minutes you know what people had for dinner. After your nose shuts down you tune it out, but those particles didn't stop winging it from the prawn heads into your breathing tract. We can't easily tell we're breathing in diesel particulate matter and like, unless you happen to walk by an airport at the right time to get a whiff from a passing jet, but the fine matter is there, smelt or not.
I sometimes think that wheezy asthmatic non-sports kid down the back of the class is the canary in the coal-mine: if they're having a bad day, actually everyone in that room might be.
For the first year of my new Apt, every time we came back in from shopping we got a whiff of a lovely "new house smell" -the complex VOCs include the formaldehyde in the construction materials out-gassing. That stuff isn't good for you: https://en.wikipedia.org/wiki/New_car_smell
Was it only used for the calibration?
If so, that would be a shame, as I am precisely looking for an inexpensive but reliable NO2 sensor device.
That's what I did when the air was unbreathable with an AQI ~ 900.