I'm looking at the Airthings 2989 View Radon to control my Radon exhaust fan. Short term readings of 24 hours are way too long. Does anyone know if the short term hourly reading is available in the integration?
When we took radon readings a few months ago it took three months.
I would guess there is a reason why most professional solutions take weeks or months
With my Wave+, the short term radon is updated hourly in home assistant. Whether one would want to control an extractor fan with that information, I don't know.
ed. I guess I should clarify that it's the previous 24 hour average that's being updated hourly.
Thanks for clarifying the hourly update! I have one now that updates the six hour average every hour and I control the fan manually. But I cannot integrate it, it doesn't even have wifi. My radon readings will stay low for days at a time sometimes without the fan, it seems pointless to have the fan running. It uses power and pulls outside air into the foundation, which affects the HVAC. However, the only means I have of reducing the radon when it gets too high (I picked 2.0) is just natural dispersion (unless we can open the windows). So I do want to know as early as possible if it is spiking.
Overall exposure matters here, not some occasional spike. Theres's no practical difference if you have 9 days of 1.0 and one day 2.0 compared to 10 days of 1.1
This is true, I just don’t see the point in running the fan when the levels are naturally low.
Neither do I.
And if your averaged levels are low as well, you can forget the fan completely.
If your spikes disappear in low average levels, you don't need to consider them.
If you have five days a week <1 and two days >5, it would make sense to switch the fan on for those high level days because their effect on average exposure is significant.
Exactly! (Old controls engineer here 
)
I decided on the EcoSense EcoQube. It updates every 10 minutes and plots the graph once per hour. With the graph you can look at long term readings. There is no native Home Assistant integration, but there is a custom available in the HACS. It works well. I have it turn on the fan above 2.0 and off below 1.
The only radon detectors that are fast enough for real-time mitigation controls are laboratory grade and obscenely expensive. Some consumer devices will spit out a number, true, but they cannot be trusted if the radon level is changing rapidly.
If the level jumped high enough to become dangerous, it would likely be too late to open air vents or reduce pressure in an ASD system. In fact, such a system would lag so badly that exposure danger may have already passed by.
It's good to think of radon detector accuracy as "bands of exposure time". Most specs give two numbers (short term and long term). Often "short term" is 3 days, and "long term" is a week. If the spec says 10%, it means the reading has an error within 10% only measuring a STEADY radon level for a full week. Anything else has no spec, so who knows.
Yes, every other one I researched would only update the short term every hour, the short term being 24 hours. So that is pretty useless for fan control. This one gives an actual reading every ten minutes, which is what I'm using to control the exhaust. Below is what it looks like in HA.
I'm kind of surprised the level changes that quickly after the fan starts since I'm not actually ventilating the room, just the foundation.
In the case above, the fan started running at 2:46 pm and stopped at 10:56 pm.
I have my setpoints at 2.0 and 1.