SAN DIEGO -- Radon is an invisible gas that you can't avoid. And yet too much exposure can cause cancer. But is it also coming from a source in your home that you never considered? The I-Team takes a practical look at the concerns about granite and radon.

Granite countertops are popular and attractive. Homeowners like its beauty, durability and the ease of cleaning solid slabs with no grout lines. Prices have also come down over the years.

"It was an easy decision," said homeowner and I-Team producer Felicia Kit about choosing granite countertops.

But has remodeling this kitchen come with a hidden expense?

"There's the risk to my children that really scares me," said Kit.

After recently installing granite countertops, Kit learned of a health warning circulating about some granite countertops emitting radon.

Radon is a radioactive invisible gas that is naturally found in the earth. It comes from the decay of uranium in soil and rocks -- including granite.

According to the Surgeon General, radon is the second leading cause of lung cancer in the United States after smoking.

The news is spreading quickly -- just ask Greg Elmassian, Director of Operations at Bedrosians. He sells granite slabs in North County.

"The last few weeks people have been coming in -- asking should I get rid of my granite, what should I do?" said Elmassian.

That's a question the I-Team wants to help answer.

We put Kit's granite countertops to the test ... using two different methods.

"I went on the California Department of Public Health website. I took their advice. I ordered three canisters to test radon levels in the home," said Kit.

Kit followed the directions on the agency's website and placed the charcoal canisters in three different rooms to test the radon levels in the air.

We also contacted a California certified radon tester for the second method of analyzing radon levels. Darioush Ghahremani, president of Radon Survey Systems, Inc., has a doctorate in geology and geochemistry. He has over 26 years of experience in radon and other soil gas geochemical surveys.

"All granite will have some radiation, and the radiation can vary," said Dr. Ghahremani.

According to the Environmental Protection Agency, indoor radon levels should not exceed four picocuries per liter of air. That level of exposure gives you about the same risk for cancer as smoking a half a pack of cigarettes a day.

Ghahremani uses an electronic monitor to scan every inch of countertop in Kit's kitchen for a quick check.

"Right now I see some (radon emissions), but it's not that much," said Ghahremani.

For a valid reading, both the continuous radon monitor device and the charcoal canisters are left in place for at least 48 hours.

While the home test is taking place, the I-Team heads to a granite slab yard where Ghahremani uses a handheld Geiger counter to test for levels of radiation, which may indicate if radon is present.

Out of the random sampling of slabs that we checked, one of the slabs from Brazil tested higher than the others. Its Geiger counter reading showed 0.13. Although that doesn't indicate whether the radon emissions from the slab inside a home would cause a problem, Ghahremani would use the number as a comparative value and recommend choosing a slab with a lower reading.

Elmassian said, "We're intending on buying radon gas measuring equipment just to do a first cut, to see if there is a problem or not."

If they are able to do so, it could ease the store's and consumers' peace of mind.

Meanwhile, the tests are completed at Kit's home. Both the charcoal canister test and the continuous radon monitor device indicate that the measured radon levels in her home are well below the EPA's action level.

"I feel much better," said Kit.

The granite here is safe.

To learn more granite and radon, indoor radon risks, and how to conduct a reliable test in your own home, read producer Felicia Kit's blog on the subject here.,