What should be recommended if a short-term test result is above 4.0 pCi/L but less than 2x that?

If a short-term radon test result is above 4.0 pCi/L but less than 8.0 pCi/L (which is twice the 4.0 pCi/L threshold), it is advisable to either conduct a second short-term test or a long-term test. This recommendation acknowledges the need for additional assessment to confirm the elevated radon levels, as short-term tests can sometimes yield misleading results due to variations in environmental conditions, such as weather and ventilation changes.

Performing a second short-term test can provide a more immediate understanding of the radon levels, especially if the first test was influenced by temporary factors. On the other hand, a long-term test gives a more accurate estimate of exposure over time, which is critical for making informed decisions about mitigation.

This approach balances the need for prompt action with the understanding that radon levels can fluctuate, promoting a thorough examination of the situation before determining the necessary steps for remediation.