The validity of doing radon tests

I wanna peoples thoughts on this. I’m going to be finishing my certification soon and i’m wondering if i should be doing radon tests for an extra fee. I’m almost done the internachi courses and it doesn’t seem like a good idea for a home inspector to perform this service unless he/she is going to do test that takes a few months. But from what iv’e seen is that most will do 48 hours. But that’s not even remotely going to give you a good reading unless the costumer is only going to be living at that house for another 2 whole weeks. There are so many factors that can change the amount of radon that enters the home the only really good way for testing would be a long term test to gives you the yearly average. Most people live in a home for more than 2 weeks so the long term average would be not only more accurate but far more important. You could do a short term test that says its only around 1.3 (pCi/L) because all the various factors equate to that amount for that time period when in reality the average per year could be 20(pCi/L). It seems like it would give the costumer a false sense of security. And if you explained that the test isn’t going to be that accurate in fact it could be very very inaccurate then mine as well direct them to a company that does lengthy radon tests. It just doesn’t seem very honest to charge someone money for a 48 or 72 hour test unless i’m missing something. I do just wanna reiterate that i’m under the assumption that a’lot of inspectors do very short term tests. So anyways just wondering everyone’s opinion on this matter.

Steven, that is precisely why I never did radon tests…along with having to make two trips to the home.

You’re thinking is good. IMHO

P,S, Welcome back to our forum! Enjoy! :smile:

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48 hour test is how it’s done during a real estate transaction. That’s just the way it is. If you don’t feel like doing it that way someone else will.


,and that will give you more time to do another inspection making more $, is how I looked at it. :smile:

Just my Opinion…

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Read the story about how Radon was discovered in homes.

If the test reveals high levels of Radon in 48 hrs you can be pretty sure your going to get it all year long. Someone else will mitigate and retest. If a young couple is going to raise a family in the home they will want to know it’s safe. Radon does kill. Sure it takes a long time, so does smoking.

The county I live in requires a well yield. It’s a point in time test. no guarantee the well won’t dry up in a dry year or how much rain is required to keep the pump submerged. Just do the test. Don’t try to extrapolate long term results from a short term test.


Everyone does a short term test. The EPA allows 48 hour measurements. There is nothing dishonest about doing this. Sure, it would be more accurate to do a 2 week long measurement, but that’s just not practical. You also have to consider that most inspection windows are 10 days long. The realtor will want the radon results ASAP so that they can negotiate mitigation if the average comes back high. While I understand your concern, this is simply the way it is. As Christopher said, if you don’t want to do it, someone else will. The driving is a burden, but I supplement my income pretty well doing radon testing.


I was privy to a test that was being conducted and the home buyer was told not to come and go too often and to make sure the doors and windows remained closed. In my opinion that would skew the test to abnormal readings.

Yea, so that is BS. Windows and doors closed 12 hours before testing, come and go as one usually would.
No air exchanging devices such as window fans. Operate HVAC as usual.

I got licensed and offer the service do it is one stop shop for clients. 3+ years

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Here’s where the protocol comes from: EPA: Standards of Practice and
ANSI AARST protocol for homes

48 hour test is totally valid. Closed house conditions required, 12 hrs prior to start of test plus duration of test. For long term, which gives more reliable results, I like the Alpha Track monitor (do an internet search). Closed house conditions not required for Alpha Track if testing for 6 month + 1 day or longer. AT monitor is good for long term, after 48 hour post mitigation test.

For mitigation questions, 48 hours is fine.

As a home inspector, one should include the radon warning statement in your report. Good liability coverage, and required in my State: Radon Warning Statement

I got in to radon testing on request of several realtors. We’re now a licensed state for radon testing. It’s good for my business; radon is an ancillary service add to the income from a home inspection. I do charge for the extra trips; base fee for radon test plus mileage.

One learns all this stuff and the answers to the above questions by getting trained and certified by the National Radon Safety Board. It’s just like getting certified by InterNACHI for home inspections.

Radon testing is like home inspecting; both have their own unique knowledge base. There’s a lot involved in assuring reliability and accuracy, and documenting it all: Monitoring for tempering, knowing closed house conditions weren’t maintained, knowing your devices are reliable and accurate… It’s the difference between setting a radon monitor and performing a reliable radon test.

EPA publications; Home Buyers and Sellers Guide

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But i can say the same about the opposite. If you do that test for 48 hours and it comes up as 1.3 (which again isn’t really an accurate reading in the long term or even a 2 month period) but for a large portion of the year its 12.0 then they can be put in just as much danger as with what your saying. If the costumer is actually concerned about radon then they shouldn’t be wasting their money on a 48 hour test. They should be getting an accurate and long term test cause as i said all your test does is show the level of radon in at that exact time. That doesn’t show what its going to be not even 3 months from now. And with such a life threatening condition getting the most accurate reading i believe is more important then the inaccurate 2 day test we can provide. Again most people live in their homes for years not weeks. Whats going to be more valuable to the costumer in terms of health and finances? A two day test for a home they will probably live in for many years. Or a test done over a longer period of time in a home they will probably live in for many years. Not only that but getting a test that is long term gives you far more insight into the homes potential radon problems and what possible solutions that could fix it. I do wanna say i’m open to having my mind changed. I’m new to this whole thing i just need to bounce ideas of some people with more knowledge and experience then myself. Also with the 48 to 72 hour tests what does that really prove? That out of 365 days a year 2 or 3 days of them has a radon level of X. Even if the levels are indicative of the period around those days It wouldn’t be more then a small period of time. As we all know the conditions in a home can change drastically within a small amount of time its unrealistic to try and pin down anything accurately let alone a deadly radioactive gas especially within 48 to 72 hours.

Or that 2 day test may be similar to the following two days and so on and so on. A 2 day test will reveal radon concerns and can lead to a longer test duration if needed.

Don’t test then! In fact, here’s my advice to you: Don’t even inspect the home! You can’t assure your clients that the outlet, GFCI, whatever will still work after you leave.

I can tell you’re a deep thinker. You should buy a shovel now!


In my opinion… A home inspection is a “snapshot” of the conditions at the time of the inspection. It doesn’t mean something wont break or work tomorrow or didn’t work yesterday but it works today. A 48 hour radon test is really no different.

The county (Montgomery County MD) where I do the lion’s share of my inspections requires a 48 hour radon test for any residential RE transaction with the exception of dwellings above the 1st floor… like a 2nd floor condo. So I have several continuous monitoring units and always have a couple working in the field. They do generate income for me. My only cost is the unit itself and calibrating once a year for around $100 plus postal fees. It is the Seller’s responsibility to provide the test results but there are no regulations in place so most buyers usually have the test done themselves. They don’t want the seller to cheat. Usually the sellers use the cheap canisters from HD or hire someone like myself. It’d very easy to dispute a charcoal canister test, harder with a computer generated printout from the CRM. I use that as a selling point. I also try to keep the unit in the house for at least 12 hours past the 48, just to avoid disputes on accuracy. 3 full days if possible.

My pricing fluctuates. If it’s a radon only job, I charge based on mileage. I generally have a flat rate if I’m already doing the home inspection and charge a little more if the inspection is further away. My business card is taped to the CRM so I’m basically advertising in the home of a person who is moving… Talk about the perfect direct marketing and I’m getting paid to do it. My machines pay for themselves in 8 tests. I buy cheap tripods and glue a mounting bracket on the bottom of the CRM.

If I test above 4.0, almost always the seller will either have a mitigation system installed or credit the buyer approx $1000 at closing. If they don’t and the buyer backs out, the seller is now legally bound to disclose high radon levels to future shoppers. IMHO, this service greatly helps my client. In my report disclaimer, it is suggested that a long term test be performed for more accurate results. But, there isn’t time for that in the 10 day contingency window.

I suspect more counties will follow suite.


The 48 hour test is not perfect but it can reveal radon concentrations requiring mitigation.

I only offer them within a limited distance from my home base or its just not worth it.

Often I will just arrange the test with a local provider as a conveiniece.

It’s still good practice to do a longer term test after purchase to get a more reliable test result.

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I’m trying to get my head around radon testing at the moment and have some follow up questions. I defo appreciate any advice. So imagine a seller knows that their property has a high level of radon (over 4 piC) and a client wants a radon test. I place the CRM in the property in a good location and request the closed air flow conditions to the seller and ask them not to disturb the unit. The unit has a tamper detection advice, etc but the seller opens up doors, etc as soon as i leave, etc to obviously limit the radon in the house.

The radon test come back low and there is very little evidence to show that the doors were left open. It seems like it would be very easy to skew a test if a seller wanted to. Anyhow so the client purchases the home but finds out later - the radon in the house is high. Now - I’m in trouble because I didnt originally detect it. Does anyone have any thoughts on this? I apologize if i am down in the weeds with this but this is how I unfortunately think sometimes.

Also does anyone has a radon preinspection agreement for the CRM because the Nachi agreement is all about sending the charcoal canisters to a lab, etc.

I don’t think you are in trouble if something was sufficiently hidden from from you. Now if the signs of tampering appeared on the charts and you overlooked them, then that’s a different story I suppose.

I think you will find it rare that anyone attempts to tamper with it. Most sellers just want to have the test and the inspection go smoothly. It is best if you provide a non-tampering notice to the seller, giving them the information they need to make sure they don’t inadvertently skew the results.

Also, if you sense that a seller may tamper with it, you can always mention that opening windows does not necessarily mean a lower reading, and that in some cases it can increase the reading.


I thought I heard once that the threshold for mitigation used to be 10 pCi/L but can’t find that referenced anywhere. If that were the case I have always suspected they lowered it to 4 due to the relatively poor 48-hour tests that are often done. Meaning, if it reaches 4 in a bad test it could get over 10 (the real level to be concerned with) during seasonal fluctuations, etc.

My company has done thousands of radon tests and can tell you it is a money maker even with the two stops. It helps to conduct enough tests that you’re combining trips to drop and pickup equipment.

I agree with all the opinions that it’s a crappy test but also agree with the person that said if you don’t do it someone else will. Any testing is better than none so I don’t think you’re doing any disservice to anyone. We hammer home to people in literature that the test has its limitations and to retest if they are borderline or just want to know. I regularly tell people to get a test at the hardware store and leave it up for a long time. They only pay me $165 because we have to make two trips and buying/maintaining the machines is expensive. The DIY tests are much cheaper and better since they cover a longer period.


Here are a couple of snip-its from an agreement I would incorporate into your final agreement.

The results of radon testing is not a guarantee that radon does or does not / will or will not exist in the subject property; the results are indicative only of the radon level in the areas sampled at the time the service is performed.

If the test conditions in this agreement are not adhered to, the test results may be deemed invalid and We shall not be held responsible for any consequences or fees that should occur,

Now I have had situations where the test was invalid due to circumstances out of my control. In these situations, I notified my client the test was invalid and why. End of story there.

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radon.pdf (46.2 KB)


Beautiful replies - this has been melting my head. Ive been spending weeks looking at pre-inspecion agreements, etc. Driving me to drink more. Anyhow thats a big help. Appreciated.

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