Granite Countertop Radiation Explained


What kind of radiation does granite emit? Within the veins of the stone radioactive uranium, thorium, and radium naturally occur. True, these levels are usually in such small amounts that they pose little risk, especially if you get some distance from the countertop. However, occasionally, I will bump into a countertop that emits higher than 100 CPMs (counts per minute.) This is too high for my comfort level and should be for yours, also.

Why? Let's put this into context. An average person living at sea level (NYC) acquires about 300 millirems of naturally occurring ionic radiation per year. article on radiation exposure.  


100 CPMs translates to 10 millisieverts per hour or 333 millirems. Therefore, for this example, the average yearly exposure is doubled. If you are in your kitchen several hours per day preparing meals, a 100 CPM level could present an unsafe issue. If you are not in the kitchen very much, then this is not very significant.

Granite countertops can measure as high as 300 CPM. This is over 1,000 millirems, which is too high.

Another stat to add context: the Federal Government places a restriction of 500 millirems maximum exposure for anyone under 18 years old who works with or near radiation. 5,000 for an adult. The EPA recommends that our exposure to background radiation should not exceed 100 millirems a year.



The real problem with owning a granite countertop that no one ever talks about is that radon gas is a natural residue of the radioactive decay of radium. Radon gas is the second leading cause for lung cancer (second to smoking.) The levels of radon gas emitted vary from stone to stone. In some homes, the radon gas emitted from the ground into the basement is much more of an issue. (BTW, we provide state-of-the-art digital radon testing.)

Fortunately, radon gas in the kitchen can be diluted by increasing air flow, as with other toxic volatile organic compounds, by introducing proper ventilation to the area. The problem often occurs in colder climates during winter-time when no one wants to leave a window cracked open or have their loud exhaust fan running continuously.

So, if you do have granite countertops and you want to be confident that they are safe, we can test them with our pancake style Geiger counters which are sensitive enough to detect the smallest amount of radiation. Don't guess. Be sure. 

Here's the link to our testing: Radiological Testing