I am planning to purchase the DIY Pro Kit and TVOC Module (when it’s available). Is there still space in the Kit to integrate a Radon Sensor if the TVOC Module is added? What are the recommended Radon Gas sensors for integration?
Radon gas is known to cause lung cancer and one would argue more important than other sensors. I feel this capability should be a priority.
Nice question, I am also interested into “upgrading” the sensor capabilities!
Besides radon (and CO2, TVOC), any more suggestion important to health? CO?
As a community, we could list and prioritize air quality concerns into different groups. One for health (TVOC, pB, NO2, and Radon). One for comfort (humidity and temperature). etc. I am no scientist, but it would give your average person a better idea of what sensors they would need. Air Quality is a deep rabbit hole.
The EPA oddly enough, doesn’t even speak about Radon in their Air Sensor Guidebook.
There isn’t really any room in the case for an additional sensor (you might be able to trade some space).
Other than finding room, the integration of many kinds of sensors that use standard serial bus connections should be relatively simple if you would be comfortable soldering additional wires to the relevant pins on the microcontroller. Patching the software to add capabilities is also pretty simple if you are so inclined.
Yes it makes sense, but equally important it would be the information about which sensors are the best: their accuracy vs the price 
Thanks for the info. It’s hard to tell for a person who does not have one.
I have experience soldering and coding. I have little experience with Arduinos or Pis as far as integration. I built a PiHole before though.
I spent a short bit of time looking for sensors. I found something that seems to be a radon detector, but it is a surface mount device. That solves the space problem, but raises the problem of soldering to a new level.
The solution would be to find somebody who has built a small board to hold the sensor that has some space for pins. I haven’t seen anything like that.
I am also surprised by the small size. I know that you can detect radon using laser absorption or with a geiger counter, but neither of those would be small.
Sorry not to be a source of useful information!
This is useful! But it would be even more useful if you shared a link to what you found!
Soldering is not that big of a problem for me, i think what matters is whether it can be used in the I2C bus…
It seems like this device is basically what you found out there, e.g. here it is on aliexpress. It has two major problems:
The good news is that it’s basically based on the I2C bus as well, if I read the pinout correctly. So if you make your own case and solder the pins to the spare i2c bus, you might be able to flash the firmware and read radon values on there!
Typically though, what I understand from radon is that you check if you’re vulnerable, then install mitigations (like venting) and monitor that. And then there are sensors that are much smaller and could fit inside the device, see this guide from digikey. Just to be extra clear here: that device doesn’t monitor radon! It monitors pressure to make sure radon is properly taken care of.
So if you’re worried about radon, the first thing you should do is buy a dosimeter. You put that in your basement or wherever you’re worried about radon concentrations, leave it there for a few months, then send it back for analysis. If you have radon, you implement mitigation measures, if not, yay, don’t worry about radon!
The problem with monitoring the “mitigation” is that radon infiltration can vary quite a lot based on changes in groundwater levels (after rain), temperature, hvac use, and pressure. My home levels have varied by a factor of at least 8x on different days.
So your mitigation could be pronounced sufficient in the summer, when radon levels are low, but spike past safe levels in the fall, winter, or spring due to temperature and rain. Without actually monitoring radon itself, you won’t know.