How can indoor air quality be affected by outdoor factors during radon testing?

The choice highlighting that changes in outdoor temperature can influence air pressure is correct because air pressure differentials between indoor and outdoor environments can significantly affect the movement of gases, including radon. When outdoor temperatures fluctuate, they can alter the density of the air outside, which in turn can create a difference in pressure that draws air into the building. This process may lead to increased radon levels indoors, particularly if the structure has a direct connection to the ground or a basement where radon is more prevalent.

Understanding this dynamic is crucial for accurate radon testing, as it emphasizes the importance of considering external weather factors when measuring indoor radon concentrations. Wind speed, humidity, and outdoor temperature are all elements that can easily change and directly influence indoor air quality, especially regarding the entry of radon gas.