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Thread: Granite....radon

  1. #1
    Plumber jimbo's Avatar
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    Default Granite....radon

    Has anyone been reading about this issue? My daughter decided to buy one of those test kits, and sent in to the lab for results. It came back with 3 pico-curies. The lab danced, and basically said that is not high enough to panic and too high to just ignore. But doesn't say WHAT to do.

    We are in an area where naturally occuring radon from the ground is basically not existent, so we assume these numbers are the off-gassing from the granite.


    There seems to be a ton of info on this on the internet, but I have not come across an authoritative source which will say whether this off-gassing from the granite is something which is worrisome, like the stuff that comes up from under the house.

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    Nowadays everything will kill you. You can't even eat a damn chicken anymore.

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    Plumber Cass's Avatar
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    My dad is fairly well versed in this...I will ask him later today and report back.

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    Radon Contractor and Water Treatment 99k's Avatar
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    Quote Originally Posted by jimbo View Post
    Has anyone been reading about this issue? My daughter decided to buy one of those test kits, and sent in to the lab for results. It came back with 3 pico-curies. The lab danced, and basically said that is not high enough to panic and too high to just ignore. But doesn't say WHAT to do.

    We are in an area where naturally occuring radon from the ground is basically not existent, so we assume these numbers are the off-gassing from the granite.


    There seems to be a ton of info on this on the internet, but I have not come across an authoritative source which will say whether this off-gassing from the granite is something which is worrisome, like the stuff that comes up from under the house.

    I am very familar with this problem. I just tested someones house yesterday ... their well water, basement air, upstairs air, and geiger counter of the granite. Tests have determined that an average countertop will contribute about .13 pCi/L to a house average when the threshold action level is set at 4 pCi/L. Does she have a basement or does she live on a slab? Does she have city water or well?

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    Plumber Cass's Avatar
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    jimbo, how many days long was the test, what room was the sample taken from, the house windows should have been closed, AC being on may cause it (the reading) to be lower. With max of 4 pci/l if it was a 1 day test that could be a false negative or positive. 1 day tests are not good and conditions in the home should simulate winter conditions during testing...every thing being closed up.

    Does any one in the home smoke in the house? Smoking exacerbates radon.

    The test should be done in the room where they spend most of their time which is normally where the TV is.
    Last edited by Cass; 08-22-2008 at 06:15 AM.

  6. #6
    Radon Contractor and Water Treatment 99k's Avatar
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    Quote Originally Posted by Cass View Post
    jimbo, how many days long was the test, what room was the sample taken from, the house windows should have been closed, AC being on may cause it (the reading) to be lower. With max of 4 pci/l if it was a 1 day test that could be a false negative or positive. 1 day tests are not good and conditions in the home should simulate winter conditions during testing...every thing being closed up.

    Does any one in the home smoke in the house? Smoking and radon together is worse than either one alone.
    Having the A/C on is perfectly fine as long as you are recirculating the air and not introducing new air. As far as the location, please confirm the kit WAS NOT ON THE GRANITE. Should be 20" off floor, 3' from an outside door or window, and 12" from an outside, 4" from other objects.

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    Moderator & Master Plumber hj's Avatar
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    Default testing

    radon testing is like going to the optometrist. According to them EVERYONE needs glasses and everyone has a Radon problem.

  8. #8
    Radon Contractor and Water Treatment 99k's Avatar
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    Quote Originally Posted by hj View Post
    radon testing is like going to the optometrist. According to them EVERYONE needs glasses and everyone has a Radon problem.
    The only problem I have with that statement is that approximately 22,000 die each year from radon induced lung cancer ... when I loose my reading glasses I just need to stretch my arms

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    Plumber jimbo's Avatar
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    The house is on a slab, cith water. According to any maps I have found on the internet, this is a "low" area for natural radon.

    She bought a kit which had 3 cannisters. She did all three in the "great room" which is kitchen/dining/family combo. But none right on the granite. A/C recirculates, but 2 little girls who hate to close the doors allow a lot of outside air in!

    I was thinking of buying one of those machines ( geiger counter ??) which allow you to do repeated tests, and accumulate short term ( few days ) and longer term results. About $120. Looks like another toy I need!

  10. #10
    Radon Contractor and Water Treatment 99k's Avatar
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    Quote Originally Posted by jimbo View Post
    The house is on a slab, cith water. According to any maps I have found on the internet, this is a "low" area for natural radon.

    She bought a kit which had 3 cannisters. She did all three in the "great room" which is kitchen/dining/family combo. But none right on the granite. A/C recirculates, but 2 little girls who hate to close the doors allow a lot of outside air in!

    I was thinking of buying one of those machines ( geiger counter ??) which allow you to do repeated tests, and accumulate short term ( few days ) and longer term results. About $120. Looks like another toy I need!
    Well, I don't see anything that would indicate these tests are invalid as long as she followed the protocol of heights and distances that I listed before. Also, you don't want to take measurements directly in the kitchen. Understand high radon is in every state and in every country ... don't read too much into local maps.

    You do not need a geiger counter because a good one will cost you $600. A Continuous radon monitor runs anywhere from $600 to 10K. I have a continuous radon monitor and have found good correlation to a device called a Safety Siron. This device looks just like a plug-in CO detector. You can buy them on e-bay for ~$100.

    Anymore q's, fireaway because radon contracting is my business.

  11. #11
    In the Trades Bob NH's Avatar
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    Radon comes from decomposition of radium, which is often present in granite.

    If there is graninte under the slab or basement floor, the gas is trapped and tries to escape through the floor, which almost always has some cracks or joints. It is practically impossible to make the floor gas-tight.

    I helped my son install a mitigation system in the basement of his home in Vermont. The level was about 8 before installation and about 1 when we tested after we finished.

    The principle of the systems is to use a blower to create a vacuum under the slab or floor so the pressure under the slab is lower than the pressure in the basement or room. The connection is made with PVC pipe sealed into a hole (or holes) in the floor, run to the blower in an attic or other convenient place, with the exhaust through the roof. You can run it out the side of the house if it is not near a window.

    Effectiveness depends on having a porous layer (gravel or coarse sand) under the concrete so the gas and air can pass under the slab to the collection point(s).

    The cracks and other openings in the floor should be sealed as well as possible so the blower size can be minimized. That is because power consumption can be significant. A 100 watt blower uses about 72 kW per month which can add $10 per month to the electric bill.

    We caulked all around the edge of the basement floor, around the toilet in the basement, and around a drain penetration.

    With the level that you have it would be worth investing in the continuous radon detector. I suspect that radon will be down in the summer with all of the inside/outside traffic and ventilation, and you could shut off the system to save power.

  12. #12
    Plumber jimbo's Avatar
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    Yes. The Safety Siren is the one I was looking at.

    Problem with this issue is getting a straight answer! Some sites ( probably related to the granite industry!) suggest not to worry about localized readings off the granite....it is just the whole house number which matters. Who knows! Granite kitchens have been around a long time, and I have never heard that they have connected any cancers to that....but who knows!

    I am not paranoid about the issue...not a stranger to radioactivity. As a whippersnapper, I have slept within inches of a nuclear tipped subroc rocket. The made us sleep at the rocket motor end, not up at the warhead end! Also breathed enough CO, CO2, and R12 that a few stinking picocuries of something won't phase me!

  13. #13
    Radon Contractor and Water Treatment 99k's Avatar
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    It is good advice not to worry about the granite and concentrate on the total radon levels. As I said, the average granite top is adding .13pCi/L which is pretty low.

  14. #14
    Radon Contractor and Water Treatment 99k's Avatar
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    Quote Originally Posted by 99k View Post
    It is good advice not to worry about the granite and concentrate on the total radon levels. As I said, the average granite top is adding .13pCi/L which is pretty low.
    Quote Originally Posted by Bob NH View Post
    Radon comes from decomposition of radium, which is often present in granite.

    If there is graninte under the slab or basement floor, the gas is trapped and tries to escape through the floor, which almost always has some cracks or joints. It is practically impossible to make the floor gas-tight.

    I helped my son install a mitigation system in the basement of his home in Vermont. The level was about 8 before installation and about 1 when we tested after we finished.

    The principle of the systems is to use a blower to create a vacuum under the slab or floor so the pressure under the slab is lower than the pressure in the basement or room. The connection is made with PVC pipe sealed into a hole (or holes) in the floor, run to the blower in an attic or other convenient place, with the exhaust through the roof. You can run it out the side of the house if it is not near a window.

    Effectiveness depends on having a porous layer (gravel or coarse sand) under the concrete so the gas and air can pass under the slab to the collection point(s).

    You can effectively remediate a building without having porous material if proper techniques and equipment is used

    The cracks and other openings in the floor should be sealed as well as possible so the blower size can be minimized. That is because power consumption can be significant. A 100 watt blower uses about 72 kW per month which can add $10 per month to the electric bill.

    This is not necessary in most instances ... especially is a home that is finished and on a slab

    We caulked all around the edge of the basement floor, around the toilet in the basement, and around a drain penetration.

    With the level that you have it would be worth investing in the continuous radon detector. I suspect that radon will be down in the summer with all of the inside/outside traffic and ventilation, and you could shut off the system to save power.
    You should never shut down a system. The radon level will be back to were it was within hours. Not only does a system remove radon, but can mine out as much as gallons a day of moisture. Many of my clients have seen the dehumidifier run much less and the musty smell is gone

  15. #15
    Moderator & Master Plumber hj's Avatar
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    Default radon

    I guess when the class action lawyers start advertising for clients, that is the time to wonder whether this is the new "asbestos" scare. They didn't get much business the first time around with Radon, so maybe this time is the charm.

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