In a simultaneous testing method, if one reading shows 7.8 pCi/L and the other is 2.9 pCi/L, what action should be taken?

The appropriate action in this situation is to perform a retest because there is a significant discrepancy between the two readings. In radon testing, when simultaneous readings yield significantly different results, it is crucial to ensure accuracy before taking further steps, such as mitigation.

Retrieving a second set of readings helps to confirm whether one of the readings was erroneous or if there is variability in radon levels at that specific time and location. The initial results can sometimes be influenced by factors like the transient conditions of the environment or equipment issues. Retesting ensures that any actions taken regarding radon mitigation are based on reliable and consistent data, ultimately ensuring the safety and health of the occupants.

Immediate mitigation based on the higher reading without further investigation could be premature, as it may lead to unnecessary expenses or actions based on potentially inaccurate data. Accepting the higher reading without retesting risks overlooking important information regarding the radon levels in the environment. Discarding the lower reading without evaluating it further would also not provide a comprehensive understanding of the radon levels present. Therefore, retesting is the most prudent step to take in this scenario.