VHS Air Quality Monitor


#1

After discussion in #laser on Slack, @mike graciously donated a Honeywell HPMA115S0 air sensor. I volunteered to donate in a microcontroller, write firmware, and get it working. And now it’s done!

It logs to https://stats.vanhack.ca, along with the other laser stats.

It measures PM2.5 and PM10 (more info). I’ve done a bit of research into how to interpret these numbers, but there’s room for someone else to do further analysis. (hint hint)

In its current position, it tells us how much particulate matter is inside VHS near the laser cutter, causing discomfort and harm to the operator and other members. Causes for high measurements would include:

  • filters being blocked/saturated
  • laser door being opened too quickly
  • air coming back inside from the alley
  • particulate from the wood shop and other activities in VHS

Firmware is here: https://github.com/vhs/air-monitor




#2

Amazing! Thanks for getting this going. The door opening smoke is so interesting. It’s easy to forget to wait a minute for smoke from your job to clear. Looking forward to seeing how this helps us improve air quality in the space and also venting to the outside!


#3

At least for smoke, we could look at putting a sensor inside the laser with an indicator when levels have dropped enough to safely open the door.


#4

Perhaps an optical sensor is all we need for this? I have some that have about a 10mm spacing between led and sensor.


#5

I had a lot of sanding to do yesterday. While I wear my own PPE for sanding, I was curious to know what was produced in the space. It turns out it is pretty crazy.

Note, that the sensor is outside the workshop, but check out the spike that occurred presumably from my wood dust.

Beyond how crazy high it got, I’m surprised how long it took for the dust to settle, as it were.


#6

I actually really like that as a cautionary “hey, these large spikes look scary, but let’s just see what that actually means in real-world effects”