Mitigation decisions for radon should be based on which of the following?

Mitigation decisions for radon should be based on results of long-term testing or averages of two short-term tests because this approach provides a more accurate representation of radon exposure over time. Long-term testing, which typically lasts for over 90 days, allows for seasonal variations and fluctuations in radon levels to be accounted for, leading to a better assessment of the average radon concentration in a given area.

When mitigation is recommended based on short-term tests alone, there is a significant risk of making decisions based on possibly unrepresentative data, as short-term tests can be influenced by factors like weather, building occupancy, and ventilation changes. Therefore, using a more comprehensive method that combines long-term testing or multiple short-term tests gives a clearer picture of the radon levels in a property.

This approach ensures that mitigation efforts are targeted effectively, potentially safeguarding occupants from prolonged exposure to harmful radon levels.