If we put a couple charcoal canisters, a pair of electrets and some CRMs in a closed room all sitting on a table and left them there for 4 days guess what we’d get?
A bunch of different results.
There is little chance the numbers would all come out the same.
If we performed the same test with the same devices and did a 3 month test then they would probably agree with one another with only slight variations.
The short term testing we do for real estate transactions is just a rough indication of radon levels.
And I tell my clients all that upfront.
What if we do a short term test and the average comes back at 3.8?
If the client seems concerned then I advise them to do a 3 month test after they move in to get a real idea of what’s going on.
I send them to RTCA.com to purchase a long term test kit.