How should you proceed with a continuous radon monitor (CRM) test if the home has not been closed for 12 hours?

When conducting a radon measurement test with a continuous radon monitor (CRM), it's essential to adhere to specific protocols to ensure accurate results. If a home has not been closed for a minimum of 12 hours prior to testing, it indicates that there may have been fluctuations in indoor air quality and radon levels, which can impact the reliability of the results.

The process of closing all doors and starting the test for 60 hours while discarding the first 12 hours allows for the stabilization of indoor conditions. The initial 12 hours, during which the house is being closed up, helps mitigate any immediate fluctuations caused by drafts or open windows, allowing the radon levels to stabilize before accurate measurements are taken. This approach ensures that when the monitoring begins in earnest, it reflects a scenario that closely approximates real-world conditions where the home is sealed, providing a better estimation of the radon levels over time.

By contrast, the other options would not adhere to established testing protocols. Simply starting the test without giving the home time to stabilize or even leaving it open fails to account for the potential variability in radon readings due to environmental factors, leading to less reliable data.