If radon decay products represent the health risk from radon exposure, why dont we just measure the radon decay products?
There are several approved devices that measure radon decay products. In fact much of the historical research that links radon exposures to lung cancer were based upon the direct measurement of the dose causing radon decay products. Unfortunately, the measurement devices used for this more definitive measurement of risk were expensive and during the late 1980s it was desired that a less expensive device be made available for consumer measurements. This gave rise to the measurement of radon gas as a surrogate measurement for estimating radon decay product exposure. Recent advances in technology have now made the direct measurement of radon decay products much more feasible and therefore allowing for a more definitive characterization of health risk.
