double testing for radon

When testing for radon, does anyone tell the client that a second test should be performed? If so, is it a separate charge or combined with the first? What do you charge per trip? I haven’t sold any radon test yet, but I’m I’ve started marketing them.
Thanks so muck, Tom

In a real estate transaction? NO. The results are the results.

That is unless the two canisters are way off. Then one of the canisters is in error. If that were the case, I would not charge for a retest.

In the case of my CRM, if I suspect tampering, I charge.

The only time a re-test of Radon levels is recommended is when a mitigation system is professionally installed.

Not true…see my previous posts. Also see the EPA protocols for both real estate transactions as well as for not real estate transactions. re-testing is recommended for several reasons.

Not true…it’s ridiculous to test twice.

I utilize two canisters side by side and that’s adequate testing for any Radon test.

If you can show the kits were tampered with, closed house conditions were not maintained, or the HVAC system temperature was changed to be outside the accepted range, I think that would warrant a re-test.

Yes indeed.

Ok… Canister one has a value of 2.0 pCi/L. Canister two has a value of 48.7.

What’s the radon level?

Radon protocols for testing with multiple canisters:

Calculating Test Results for 2 devices: Average = (R1 + R2) / 2

If both readings are below 4.0, Report the result.

If both readings are above 4.0:, Report the result recommend mitigation.

If one is above and one below: If the higher is more than 2x the lower report the indiviual results and average: THEN RETEST, investigate the cause of the error.

If the higher is less than 2x the lower report the individual results and average.

Is there a standard on how much can the two canisters can differ from each other before a retest is required?

In all the years of my Radon testing, I’ve never seen such a wide window in the Radon level test results.

I’ve never seen a difference (of both canisters) of more than 2.0.

In order to obtain the proper readings from two canister placements, you simply average out both numbers. If the average number is over 4.0…then Radon mitigation is imminent.


Canister 1 = 2.7 pCi/L

Canister 2 = 1.5 pCi/L

Add up the test results, which is 4.2 pCi/L, then divide this number by 2 which equals…2.2 pCi/L

If one is above and one below 4.0 pCi/L: If the higher is more than 2x the lower report the individual results and average: THEN RETEST, investigate the cause of the error.

If the difference is large, the presumption is that one or both of the canisters has somehow failed. Maybe it got wet, or had a leaky seal, or whatever. Since this is a real possibility, then a retest is called for.

Another reason to re-test is if you think there are signs of tampering, or if the weather conditions exceed EPA standards for any length of time (i.e. a hurricane moves in on the coast.) In these cases the value is to be reported along with an explanation as to why you are disqualifying the test. Then a retest should be performed.

For me though, this is mostly moot. I do radon testing for several reasons: 1) to promote healthy homes and clients, 2) To be able to offer a one stop shop to my clients and their realtors for inspection services 3) to make money.

I’ve found that I can do those most effectively, and cost efficiently with the use of CRM’s. Sure they are expensive up front, but if I don’t do an inspection they don’t cost me anything for rent. I started out by renting units, and when I bought my own my first one paid for itself in three months of saved rental fees. Also when I do an inspection it is fast, easy, and easy to tell if it’s been tampered with. Also I have virtually immediate results, and I don’t have to worry about doing multiple tests to make sure it’s all good.

The only time I ever use canisters is for clients who are not in a RE transaction who are located a significant distance from me. I leave the canisters with instructions for the home owner to seal them and mail them for me. (Saves an expensive trip.) Which is acceptable for Non-RE testing protocols. The other times I have used non-CRM’s is in situations where there is no electricity in the home. I don’t like doing that because normally you don’t have HVAC running under normal conditions. But I’ve had a few clients who wanted to do that anyway regardless of the protocols. It was documented, and done.

Hope that helps.

Well, good for you. That’s the way it should be. That doesn’t mean that’s going to happen all the time.

I use a CRM and over the last 2 and half years, I’ve thrown out test results on two or three occasions. Once because a huge 5 day thunderstorm with tornadoes blew through the area (re-test for free) and more than once when protocols were not followed by the home occupants (charge for re-test).

Whenever a storm comes through, I watch the average values very closely. I’ve see the values jump as much a 1.5 pCi/L when the storm passes the house. The graph of values is pretty neat to watch.

Check out the EPA’s guide to Radon and Real estate transactions.

I use an active monitoring system… the ‘tuna cans’ are notoriously inaccurate (I’ve read as much as 20%)… more reliable labs ask if the test is for a real estate transaction; if so they require that two tests to be performed.
The Rad Star unit that I use is relatively ‘tamper-proof’… i.e. I am able to track power interruptions, temp and humidity. I can set the unit, return in 48 hrs and print the results.

I hope this helps,