What assumption is often made regarding the Equilibrium Ratio for general radon exposure?

The assumption regarding the Equilibrium Ratio for general radon exposure is often set at 0.3 or 30%. This is based on the understanding that not all radon gas in indoor air is in equilibrium with its decay products (radon progeny), meaning that only a portion of the radon acts as a health hazard due to the decay products. The equilibrium ratio is important in estimating potential health risks from radon exposure because it helps to quantify the amount of radon that contributes to radiation dose.

In many contexts, particularly in indoor air quality evaluations, the assumed equilibrium ratio can vary based on factors such as ventilation, the nature of the building, and the duration of exposure. Using 30% as the equilibrium ratio allows for a conservative estimate when calculating the potential health risks associated with radon, ensuring that mitigation efforts target significant exposure risks while recognizing that some radon will remain unaccounted for in various indoor conditions.