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What kind of air quality monitor is being used here? I've been looking for a good one to purchase for myself, would be good to get one with N02 capability.

by thurn 5y ago

garrettgrimsley 5y ago
I reached out to the author and they're using an uHoo Smart Air Monitor and will be writing a review of it in the future. Most reviews of air quality monitors seem to focus on details like the size of the screen, or whether the monitor app is easy to use, and fail to actually test the accuracy of monitor itself. Hopefully this author's review is different. See this EPA testing table for some measures of accuracy: https://www.epa.gov/air-sensor-toolbox/evaluation-emerging-air-sensor-performance https://www.epa.gov/air-sensor-toolbox/evaluation-emerging-a...
- thurn 5y ago
  So, there are basically no consumer products on this table that have a respectable accuracy, right? The ones with good R² values all seem to be $1000+ scientific tools.
  - garrettgrimsley 5y ago
    Unfortunately, yes. And I wouldn't trust the uHoo marketing claims about their sensor even one bit. I found another testing table if you'd like to take a look: https://www.cabq.gov/airquality/documents/research-on-availablity-and-reliability-of-low-cost-air-quality-monitors_4-15-21.pdf https://www.cabq.gov/airquality/documents/research-on-availa...
aulin 5y ago
Any cheap sensor (electrochemical? single electrode or even dual) sold for amateur use is unlikely to provide any useful measurement, especially if you want to draw any conclusion about concentrations exceeding safety limits like the author is doing. They are a pain to calibrate, the absolute values you get cannot be trusted, the most you can use them for is to say something about trends and spikes. "Look the gas stove is on, there's a NO2 and CO spike!", now let's get a chemoluminescence spectrophotometer to see it we should worry.
- thurn 5y ago
  Hm, so you'd dispute uHoo's claim of "±20 ppb or ±10% of actual value" for their NO2 sensor?
  - aulin 5y ago
    Where do they claim that? Do they say which kind of sensor they're using? Electrochemical? Metal-oxide? These sensors usually require advanced periodic calibrations, you need to correct for temperature and humidity zero and sensitivity dependence, model sensitivity drift as the sensor ages, take into account cross sensitivities to other gases. I'm not disputing anything, I'm sure they do all that. I'd love to read some detail about it or a third party review that did a comparison with a reference device. It would also be cool to place some of their detectors side by side and see how much they agree on the measurements.

What kind of air quality monitor is being used here? I've been looking for a good one to purchase for myself, would be good to get one with N02 capability.

by thurn 5y ago

What kind of air quality monitor is being used here? I've been looking for a good one to purchase for myself, would be good to get one with N02 capability.

garrettgrimsley 5y ago

I reached out to the author and they're using an uHoo Smart Air Monitor and will be writing a review of it in the future. Most reviews of air quality monitors seem to focus on details like the size of the screen, or whether the monitor app is easy to use, and fail to actually test the accuracy of monitor itself. Hopefully this author's review is different. See this EPA testing table for some measures of accuracy: https://www.epa.gov/air-sensor-toolbox/evaluation-emerging-air-sensor-performance https://www.epa.gov/air-sensor-toolbox/evaluation-emerging-a...

thurn 5y ago
So, there are basically no consumer products on this table that have a respectable accuracy, right? The ones with good R² values all seem to be $1000+ scientific tools.
- garrettgrimsley 5y ago
  Unfortunately, yes. And I wouldn't trust the uHoo marketing claims about their sensor even one bit. I found another testing table if you'd like to take a look: https://www.cabq.gov/airquality/documents/research-on-availablity-and-reliability-of-low-cost-air-quality-monitors_4-15-21.pdf https://www.cabq.gov/airquality/documents/research-on-availa...

aulin 5y ago

Any cheap sensor (electrochemical? single electrode or even dual) sold for amateur use is unlikely to provide any useful measurement, especially if you want to draw any conclusion about concentrations exceeding safety limits like the author is doing. They are a pain to calibrate, the absolute values you get cannot be trusted, the most you can use them for is to say something about trends and spikes. "Look the gas stove is on, there's a NO2 and CO spike!", now let's get a chemoluminescence spectrophotometer to see it we should worry.

thurn 5y ago
Hm, so you'd dispute uHoo's claim of "±20 ppb or ±10% of actual value" for their NO2 sensor?
- aulin 5y ago
  Where do they claim that? Do they say which kind of sensor they're using? Electrochemical? Metal-oxide? These sensors usually require advanced periodic calibrations, you need to correct for temperature and humidity zero and sensitivity dependence, model sensitivity drift as the sensor ages, take into account cross sensitivities to other gases. I'm not disputing anything, I'm sure they do all that. I'd love to read some detail about it or a third party review that did a comparison with a reference device. It would also be cool to place some of their detectors side by side and see how much they agree on the measurements.