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Testing Your Home and Granite Countertops for Radon Gas

When all the news reports came out a few weeks ago about the dangers of radon-emitting granite countertops, we got worried. The previous owners installed $4,000 worth of granite in the kitchen and we had no idea if we were poisoning ourselves or worrying needlessly.

Performing Your Own Radon Test

Now I will state up-front that I am absolutely no expert on radon gas emission or testing, although my wife says I’m a pro at general gas emissions, but I will relay our own experience with running a home radon test and getting the results.

First, I did my research through the Environmental Protection Agency’s (EPA) Website to learn more about radon and self-testing. I learned that radon can cause lung cancer and radon itself causes about 20,000 deaths per year from lung cancer. That makes radon the 2nd leading cause of lung cancer, just after smoking/secondhand smoke.

Where to Get Your Radon Test Kit

I’m sure there are a dozen ways to get a test kit, but I’ll mention two here:

  1. The EPA refers you to the National Safety Council, who provides a coupon to order a short term or long term radon test kit. The cost is $9.95 for the short term test and $20 for the long term test. They recommend you just do a short test at first to see if you have cause for concern, then do a long one if you do have radon problems to be certain of the findings. They will mail it to you, you run the test and then mail it back (probably at your own cost).
  2. While at Lowes, we picked up the Kidde Radon Gas Detection Kit for about $17, but it’s at Amazon for $15. It’s a short term test only, and probably works exactly the same as the NSC one. You run the test and mail it in using their envelope and your own postage (about 4 stamps).

We went with the Kidde kit simply because we were there at the store and didn’t feel like waiting for a month to run the test. We could be dead by then!

How to Run the Test

Again, I’ll only state our experience and what our test kit required. For the Kidde kit, you had to take it out of the plastic, place it in a non-windy, non-heated/cooled, dry location. Also you can’t have the windows open for 12 hours prior to starting the test.

Basically, the test kit is a bunch of charcoal grains that absorb the radon gas. If there is too much ventilation, then the gas will exit the home and you’ll get a false reading. And you don’t want air blowing on or past the kit for the same reason. 

You want to run the test for at least 48 hours, and you need to be exact in the date/time you started/stopped the test on the return card so the lab analysts can measure the readings properly.

As for returning the test, it cost under $1.50 to mail it, but I put on 4 stamps anyway. I also paid to track the envelope with a delivery confirmation because it needs to arrive within 10 days to be testable. It’s worthless if the Post Office loses delivers late, so be sure to mail at least first class.

Our Test Results

Surprisingly, it took 5 days after mailing to get our results. And in our case, we opted to receive the results via email. Attached to the email is a PDF document that explains your results across 4 pages.

The first page repeats the test information you entered on the information card, along with the actual reading from your test. According to Kidde, a level of 4pCi/L or higher is cause for concern and requires additional, immediate testing to confirm and act upon. A level between 2 and 4pCi/L also requires more testing, but isn’t as worrisome. And anything under 2pCi/L means you don’t need to worry.

The average home reading is 1.3pCi/L. Our reading came back at 0.5pCi/L. That means we’re surprisingly under the national average.

But what does this mean? Do we need to stop worrying? Well based on the reviews of the kit (and probably for any comparable home kit), the results may not be very reliable. Personally, I think a short term test isn’t enough to be certain as conditions around the kit can affect the results. You really need to be sure you place the kit in a prime location to collect the radon gas and not disturb it during the test period.

If you’re truly worried about your safety, I would find a certified radon tester in your area to check your home and advise accordingly.

Photo by otisarchives3

About the author

Clever Dude


  • We tested our basement and we have radon. We’re looking into how to deal with it most effectively. I’m not sure I really believe the radon=lung cancer theories. I’m sure all the VOC’s in paint and glues in homes also can cause problems. But we’ll fix it just in case. Ours is just above the limit, when I wrote the EPA they said, “You might consider to having it mitigated”.

    You have to make sure the windows aren’t open and it’s a certain heigth. I wonder how accurate those tests really are?

  • While radon exposure can be a concern, for most homes it will not be an issue. As you mentioned, radon is a heavy gas and will collect in basements, but keeping the area ventilated will disperse the gas. It would seem reasonable to do the test under the conditions in which you keep the room. Sealing it up to perform the test will cause the test to be artificially high. Radon is predominantly present in areas where there are mountains and granite (such as the north east region of the United States), and is dependent on the weather and soil since it is emitted from the decay of uranium in the mountains. If an air pocket is trapped in a valley for example, it could raise the levels of radon in that valley temporarily. Usually this is less than 1pCi/L. The amount in your counter tops is insignificant by comparison. To raise your overall chance of cancer 1% you would have to breath air contaminated at the limit of 4pCi/L continuously for 44 years: . I work in a nuclear plant, so maybe I’m biased, but most people are under educated about radiation. By the way, a banana has more radioactivity than your basement due to natural Potassium-40.

  • @Jon, that was definitely an interesting video and helps allay my fears, but then again, it seems we’re caught in a war from two parties. If anything, I at least tested the home in general for radon and my results were good.

  • We recently purchased a home which had a radon reading of 8.3. The home was built in 2004. Needless to say we included the installation of a mitigation system in our purchase agreement. The cost of the system is $1475.00 in the Midwest. The home inspector said at the level found in our home, it was equivalent to having 400 chest x-rays per year. Not sure I believe all the lung cancer/radon hype either but since we were able to get it included in the sale at the seller’s expense we felt it was a good precaution to take.

  • Is there any way to test a granite slab at the yard before purchase to see if it is contaminated? This is a valid question as it seems there is quite a wide range of readings from undedectable to extremely dangerous. I wonder if anyone has done research as to where the high emissions slabs were mined, etc. It is a shame to have to damn an entire stone if it is just from a localized area. I am planning on replacing my kitchen countertops and love the look of granite but would like to test the slab before, not after, the expense.

  • Good article, well balanced with emphasis where it should be, on the side of safety.

    Some of the comments from the public though need addressing.

    “To raise your overall chance of cancer 1% you would have to breath air contaminated at the limit of 4pCi/L continuously for 44 years.”
    Of course it is ridiculous to depend on an uranium company for unbiased info, and the EPA equates 4 pCi/L to smoking a half pack of cigarettes a day.
    And the banana dodge. Bananas won’t register using a scintillator, even if you jam the thing in the pile of bananas at Wal Mart. I know of one researcher that found a way to get a reading, he burned 100 pounds then measured the ashes.

    Jon, do really believe the granite industry is any more reliable than a uranium company? Take a look at this video.

    testing for radiation can be easily done at a slab yard, but Radon testing is cumbersome. You have to use multiple meters sealed under accumulators and even then you might easily miss the worst emitting spots.
    We have a ton of information on the issues, including actual granite testing in a sealed radon room. This weekend has fairly calm weather and the room is above 20 pCi/L, from 36 square feet of low radiation granite. The experts once said that low radiation stone was safe, but the testing done the last year has shown us otherwise, which is why we first tested some fairly hot stone, then removed it and tested low level stone (average 26.6 uR/hr with 6 uR/hr being the background radiation). That is like smoking 2 1/2 packs a day.

    The most dangerous stones almost always have uranium mines nearby, sometimes a mile away.
    for more info go to

  • Sounds good that radon testing is not out of reach now-a-days. We may have a kit and test ourselves. While this dangerous gas leading significant health risk we must control it. We need a risk free life.

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