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Comment by FL33TW00D | Hacker News Reader

I’ve been considering designing a wearable that monitors CO2 and PM2.5 continuously, but I’m unsure if people would wear it in conjunction with an Apple Watch or similar.

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This is super interesting for me - but I'd love to put it on a bicycle (they are often locked up and stationary - for example) but move at faster speeds. Maybe this means they are only useful at tracking information when locked/stationary?

I really like the idea of using cheap (?) devices in a sort of mesh to feed back telemetry data on pollution. Pollution is everyone's concern, so visualising that would be cool.

Interested to hear if you had any more thoughts on this!

Related: cheap device to track pollution + mesh + visualization: https://luftdaten.info/

Once had this thing on a balcony of a shared flat in Heilbronn, Germany. Wondered what that was, previous tenant told me about it and it was never removed from there.

Blimey, that's great! Thanks

The Bikenet project mapped CO2 in a small town:

https://www.cs.dartmouth.edu/~sensorlab/pubs/BikeNet-SenSys0...

This is neat, thanks so much!

Note that NDIR sensors use a surprising amount of power, since they're based around an incandescent bulb shining light through the sample volume. A CO2 wearable will need to be recharged once a day, like a smart watch.

I'm not sure how accurate that would be on your wrist, because the proportion of recently exhaled air would be so much higher, since it's only a foot or two from your mouth.

CO2 monitors often have little silent fans to draw in fresh air as well, for accuracy.

I don’t think it’d make a difference. I’ve got one on my desk in front of me and can’t detect a difference with me at the desk vs not.

Unless your room has really good airflow you should be able to tell quite clearly.

I have an SCD41 and I see a large spike in readings less than a minute after sitting down at my desk.

I'd wear this! This would also be very cool to share with others, form like a network to get a clearer picture of air quality

It only became possible to do it in a wearable form factor very recently using a combination of the following 2 sensors: https://sensirion.com/products/catalog/STCC4 https://www.bosch-sensortec.com/media/boschsensortec/downloa...

Not sure the market is big enough to invest my time.

> to get a clearer picture of air quality

A wearable CO2 monitor would do the opposite of this.

If you want to measure quality you need fixed location devices.

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