Radon is produced by the natural decay of uranium and radium in soil, rock, and water. 

It can seep into homes through cracks in the foundation, gaps in construction, and other openings. 

Radon can also accumulate in groundwater sources.

Testing for radon 

Radon testing is inexpensive and easy.

The EPA recommends testing all homes below the third floor for radon.

Reducing radon

Radon can be reduced by sealing cracks and other openings in the foundation. 

Radon can also be reduced by improving ventilation. 

Radon measurement 

The rate of radioactive decay of radon is measured in picocuries per liter (pCi/L).

The EPA's recommended action level is 4 pCi/L.