How accurately do radon gas measurements alone estimate health risks from radon decay products?
Devices that measure radon gas alone, estimate the amount of radon decay products in the air by a simple equation that is based upon an assumption of what percentage of the radon decay products formed from a given amount of radon remain in the air and available for inhalation. Since, radon decay products have electrostatic charges, they will adhere to fixed objects (like the interior of ductwork, walls, floors etc.). Once they attach to these fixed objects, they are not dislodged with air currents, dusting etc. In other words, they no longer present a health risk. In developing radon gas measurements as a means to estimate radon decay product exposure, the US EPA assumed that 50% of the decay products, formed from radon, remain in the air. However, this assumption can be highly variable from home to home, depending upon air movement, presence of filters (all of which reduce radon decay products in the air), or high levels of particulates in the air that provide sites to which the decay
