Radioactive Granite and Quartzite – Risks from Radon

radioactive granite and quartzite

Radioactive Granite and Quartzite – Risks from Radon

A Green Building client of ours is busy selecting interior finishes for their new healthy home. When we get to countertops the inevitable question is asked, “Are there any health concerns about natural radioactive granite and quartzite?” The answer is yes. Some quarries are producing relatively radioactive granite and quartzite slabs and tile.

The US EPA estimates that about 21,000 Americans die of radon-caused lung cancer every year. To put that in perspective, it would take only 53 days of radon-related deaths to reach the death toll from 911.

That’s really no joke. Especially if you happen to be an organic-non-smoker caught in the hospital wondering, “how the heck did this ever happen to me?”

The answer lies underground. Uranium is an unstable radioactive element. Uranium decays in a predicable order and eventually produces radon. Radon is the invisible and odorless radioactive gas that the US EPA estimates is picking us off at the rate of +/- 57 per day.

Most significant exposures to radon are due to house design and subterranean geology. The vast majority of radon sampling is based on air testing at the lowest occupied level of the building – where radon would most likely enter the building from the ground. But there are other potential indoor sources of this invisible killer.

Some granites are radioactively “hot.” The New York Times published an article about this subject back in 2008. According a worker at one stone yard I visited, the radon-granite discovery was falsified by conspirators in the synthetic stone business to handicap sales of natural stone. Sales of natural stone (at least at this stone yard) did suffer when the radon-granite connection first became widely known.

I’ve personally used a geiger counter to test many countertops, and only a couple times have I found any significant difference when comparing granite indoors to an outside baseline. Well, this week I really found a hot potato. This was the first time the “spike” was so significant it was obvious.

Story. So I meet our client at the stone yards and we devise a testing protocol. I grab an outside baseline (control) sample. We use the Building Biology threshold limits and simply place a geiger counter near several slabs to see what happens. Granted we’re inside a building (possible ground-source radon) that is full of granite slabs (other sources), and we’re taking a limited number of short-term readings, so statistically this study leaves much to be desired. But at the first stone yard all the measurements indoors were no more than 6% greater than the outside control sample. This seemed reasonable and the relationship became predictable. There were no “spikes.”  50% or greater warrants a fail according to the Building Biology threshold, so all these stones passed.

Now comes the second stone yard the following day. The outside baseline sample was nearly identical, but all the measurements indoors were significantly higher. All of the slabs the client was interested in were below the Building Biology threshold, but our interest was raised. [Oh how I’d love to do a traditional radon test in this warehouse!]

One of the attendants was kind enough to show me an orangish/red granite and indicated that when all the hub-ub was originally made it was around this particular type of granite. It was labeled Crema Bordeaux: Granite.

So I put the meter at the base of the slab as I had all the other slabs, and to my surprise the geiger counter starts chirping noticeably faster. The outside baseline was around 14 counts per minute, and at the base of the Crema Bordeaux it was humming at 42 counts per minute.

How dangerous is that? We know that ionizing radiation causes us harm. I like to refer to the Building Biology moto, “nature is the ultimate goal,” and “any reduction in contamination is worthwhile.” So whenever possible I would recommend reducing exposure to this source of ionizing radiation.

My experiment was very simple and did not account for many uncontrolled variables, but the results were rather stunning. I was lead to a particular slab that the stone yard guy said was the source of radon controversy several years ago – and Whamo – the meter spikes. Coincidence? I think not.

To close I’m going to share the horror story I was told when learning this testing method. A Building Biologist was testing a home and got a radioactive spike off a granite countertop. He didn’t say anything at first and ran a second round of tests while continuing with the environmental inspection. The second results showed a significant spike again. He mentioned this finding to the homeowner who was leaning against the counter during the conversation.

Her face changed immediately and she took a step back from the counter before raising the bottom half of her shirt to reveal a 4″ scar.

This client had a tumor removed from her belly at the exact same height as where she leaned up against the counter when she worked in the kitchen. What caused the cancer we’ll never know. Was this just another coincidence? She didn’t care.

Why not exercise precaution around this material. Granite is a lovely, durable, and readily available building material. But before you bring it into your healthy habitat have it checked out.

NOTE: We are the first to admit there are better ways of measuring radioactivity in bulk samples, but this simplified method makes for an affordable quick screening process for radioactive granite and quartzite.

10 Responses to “Radioactive Granite and Quartzite – Risks from Radon”

  1. Alex Stadtner says :

    In our limited experience we have found some quartzite with minimal levels of radiation, however particular types of granite have had significantly higher emissions rates than anything we’ve seen in quartzite. Testing individual stone slabs for ionizing radiation is really the only way to know.

  2. Tracy Chan says :

    We are interested in Quartzite. Is there any radiation from Quartzite too?

  3. Alex Stadtner says :

    I haven’t researched this fully, but I’d imagine there would be some risks from increased traffic, perhaps explosions, fine dusts generated during mining, and radiation. There may also be impacts to groundwater sources, some issues with acoustics and vibrations, etc. As far as radiation from a granite mine you’d have to do hire someone like us or buy a geiger counter and determine if that particular granite quarry is “hot.” Some granite is considerably more radiative than others – and it depends on the geology and mineral content of the particular stone.
    Good luck,

  4. Ed says :

    what are the health risks to living next door to a granite mining site?

  5. Cindy says :

    I had someone test some slabs of granite today with a Ludlum Model 3 geiger counter set on the sensitive setting which I was told was .1. The ground outside and around the granite was silent and did not move the counter at all. On the slabs I was looking at, the counter was mostly on zero. The counter unit showed a screen that went from 1-4 with smaller marked units between. The slab mostly did not move, but at times went up and hit the 1 mark. With the setting it was on, the guy said that it equalled 100 and once 120. Most of the time it stayed on 0 with an occasional bounce to 60 or 80. My question is whether this is a very good, quiet stone, or whether it is considered a hot stone. The accessor said he thought it was good, but seemed uncertain as to what is considered good and bad.

    I am glad I got the testing done, but am sitting here not knowing if this is good news or bad news. He did mention that background is usually around 40 and so at the max, my slab hit 3 times background. I did take a video, but don’t understands the results.

    Any interpretation that you might give me would be very appreciated.

  6. Alex Stadtner says :

    As a company that makes their living selling granite countertops, I can understand how this would appear threatening. You’re wise to seek more information.
    But alpha-gamma radiation have been known to harm human health since the 1930’s or before, and the technology to measure ionizing radiation is readily available at relatively low cost.

  7. Hannah Motin says :

    I don’t find the authenticity of this case as it is not confirmed by the scientists yet. But as this matter is attracting more attention from people day by day, there is fear spreading relating to this matter. I think it is time we should take this matter seriously and test how true it is.
    There should be a proper way to measure the ingredient.

  8. Alex Stadtner says :

    Hi Sue,
    I would not be unnecessarily worried. The odds are that the granite used to construct the building is not unusually radioactive. However, the only way to know for sure is to find a geiger counter (radiation meter) and collect measurements.
    Don’t worry yourself – odds are on your side – but if you want ultimate peace of mind you would have to collect some real data.

  9. Sue says :


    I was wondering about the risks of living in an old building built entirely from granite in the area near Porto in Portugal. No one there is aware of the risks. Is my nervousness justified?



  10. […] Alex Stadtner, president of Healthy Building Science, wrote a blog in April 2012 entitled “Radioactive Granite and Quartzite – Risks from Radon” about discovering high levels of radiation in Quartzite and Granite used in residential building for items such as countertops, flooring, and bath an shower enclosures.  While that blog explained very well the risks of radiation in some common natural stone, I wanted to go into more detail about measuring radiation, and what the numbers mean. […]

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