Which method is most effective in reducing radon exposure during diagnostic tests involving a shop-vac?

Placing the shop-vac outside while using the suction hose indoors is the most effective method for reducing radon exposure during diagnostic tests. This approach works by minimizing the potential for radon accumulation in the indoor environment where testing is being conducted. By positioning the vacuum outside, radon-laden air is drawn into the suction hose and exhausts outside, effectively preventing the radon from circulating within the indoor space.

The effectiveness of this method lies in its ability to redirect the radon away from the occupied areas, ensuring that any radon that may be disturbed during the diagnostic process does not contribute to increased levels in the environment where individuals may be present. This technique effectively utilizes the mechanics of ventilation and air movement to mitigate radon exposure.

In contrast, keeping the shop-vac indoors with open windows does not sufficiently eliminate radon exposure, as the radon can still accumulate within the space. Utilizing a HEPA filter, while beneficial for trapping particulate matter, does not specifically target radon gas itself, which is a colorless and odorless gas. Running the shop-vac without any suction hose would not accomplish the necessary air movement to clear out radon and would simply maintain or increase the radon levels in the environment. Thus, positioning the shop