Frequent Questions

Explain working levels (WL) and picocuries per liter of air (pCi/L).

Radon test results may be reported in two ways

Your radon test results may be reported in either picocuries per liter of air (pCi/L) or working levels (WL). If your test result is in pCi/L, EPA recommends you fix your home if the radon level is 4 pCi/L or higher. If the test result is in WL, EPA recommends you fix the home if the working level is 0.016 WL or higher. Some states require WL results to be converted to pCi/L to minimize confusion.

See our Radon Conversion Charts at - www.epa.gov/radon/pdfs/conversion_factors_rn.pdf and Radon Decay Units chart at www.epa.gov/radon/pdfs/radon_decay_units.pdf

See also our glossary of terms at www.epa.gov/radon/glossary.html

Contact your state radon coordinator, see our contact lists at www.epa.gov/radon/whereyoulive.html

Have more questions? Submit a request