Final answer:
The correct level of the home to test for radon during a real estate transaction is the basement or lowest livable area of the home. Radon gas accumulates in underground spaces and buildings with low air exchange. Testing is important because radon exposure increases the risk of cancer, and many countries have limits on acceptable radon concentrations in indoor air.
Step-by-step explanation:
The correct level of the home to test when conducting a radon test during a real estate transaction is the basement or lowest livable area of the home. This is because radon gas is typically more pronounced in underground spaces and buildings with low air exchange with the outside world. Since radon is about eight times more dense than air, it accumulates in basements and lower floors.
Testing is important because radon exposure increases the risk of getting cancer, especially lung cancer. Many countries have introduced limits on acceptable radon concentrations in indoor air and require the measurement of radon levels in a house prior to its sale. The Environmental Protection Agency (EPA) recommends fixing homes when the radon level is at or above 4 pCi/L.