Question: What are your experiences using low-cost VOC sensors outdoors? And other questions about accuracy.

bhamster is asking a question about air-quality: Follow this topic

by bhamster | November 23, 2020 22:06 | #25098

I'm hoping to build off previous posts about volatile organic compound (VOC) sensors (here about the CCS811 sensor, and here about PID sensors), and synthesize information on low-cost VOC sensors for the current research area review on outdoor air quality.

What are people's experiences using low-cost VOC sensors outdoors?

A couple of air quality researchers I've talked to say that currently available low-cost metal oxide (MOX) and photoionization detector (PID) sensors don't produce accurate data.

A few related questions:

  • What can cause these VOC sensors to produce inaccurate data?
  • What can/do people use these low-cost VOC sensors for? E.g., initial investigations into relative total VOCs, etc.
  • What's needed to improve the accuracy of low-cost VOC sensor data? E.g., hardware improvements, calibrations/corrections, etc.?

Thanks for any insights folx can share!

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4 Comments

@cfastie @sarasage The conversation you had in the comments of this post mentioned above was very helpful. Do you happen to have any updates from the field or thoughts on the questions above re: accuracy of lower-cost VOC sensors outdoors?

@robert_winkler Would you be able to share insights from MeteoMex?

Thanks to all for any thoughts, experiences, or words of wisdom you can share.

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thanks for any answers!

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Comment Author Profile Picture cfastie commented about 1 month ago

I have not used a CCS-811 VOC sensor outdoors. That's mostly because I live in the woods in Vermont and the data would be boring. However the sensor would probably document emissions from my wood stove and when trucks drive past my house.

If you live in a city or next to industry that sensor would certainly document variations in atmospheric concentrations of certain types of compounds. When deployed indoors the sensor is sensitive enough to respond to concentrations that were not possible to smell, so it would probably do the same outside.

It would be very easy for someone to test this. The components are inexpensive ($20) and the assembly has been documented and the code made available.

A couple of air quality researchers I've talked to say that currently available low-cost metal oxide (MOX) and photoionization detector (PID) sensors don't produce accurate data.

This is important information but limited accuracy does not necessarily rule out a role for these sensors. Also, it's great to see that Public Lab now seems to be open to the advice of researchers.

Chris

Thanks so much for your reply, Chris. I might give the build a try in the future, and in the meantime will dig around a bit more for existing information. And completely agree there can still be a role for these sensors!


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