The sensor in the article looks really nice (Twitter thread mentions https://www.amazon.com/Digital-Quality-Detector-Tester-Monit... as something similar. Twitter thread also links the exact product on Aliexpress, but I refuse to link Aliexpress here since that site is nearly malware).
But the problem with that sensor and all the other sensors I've found thus far (HPMA115S0, SDS011) is I can't be sure how accurate at all they are. I'm not looking for scientific grade stuff here, but if the sensor is off by a factor of two, for example, it's a bit useless isn't it? Especially if I have no idea how far off it is.
For example, I found this research paper: https://www.researchgate.net/publication/322628807_Developme...
If I'm reading it correctly they show that the SDS011 sensor is completely useless for PM10 measurements. For PM2.5 it can be off by a factor of 2 under certain conditions. They were able to come up with a calibration formula that makes it much more accurate (on PM2.5), but I have no way of knowing if their calibration formula is "universal" for the SDS011 or if the constants would vary from unit to unit.
And all of those problems on a device that is marketed as being +-15% accurate. Being off by a factor of two is well beyond 15%...
I haven't dug too deeply yet. Are there better sensors? The HPMA115S0 is brand name at least, but again I have no way of knowing for sure what its real error bounds are. Is there some way to calibrate these things at home without buying an expensive, more accurate sensor (thus defeating the purpose of the cheap sensor)?
It seems a lot of hobby projects end up using these cheap sensor anyway, even if they could be completely wrong? Maybe I'm being too picky and an error of 100% isn't a huge deal?