What is the minimum distance a measurement device should be placed from an exterior opening?

The minimum distance a measurement device should be placed from an exterior opening is three feet. This distance is important because it helps ensure the accuracy of radon measurements. Placing the device too close to an exterior opening, such as a door or window, can allow for external air influences, which may not accurately represent the indoor radon levels. By positioning the measurement device at least three feet away from such openings, any potential fluctuations in radon levels caused by drafts or ventilation effects from the outside air are minimized, leading to more reliable and valid readings. This distance is a standard practice in radon measurement protocols, aiming to achieve consistent and accurate data for effective radon risk assessment.