What information do you need to have to calculate the equilibrium ratio (ER) in a room?

To calculate the equilibrium ratio (ER) in a room, it is essential to obtain simultaneous measurements of radon and its decay products. The equilibrium ratio is defined as the ratio of the concentration of radon decay products to the concentration of radon itself. This metric is crucial in assessing the potential health risks posed by radon exposure because it indicates the extent to which radon has decayed into particulate matter that can be inhaled.

When radon gas decays, it produces a series of short-lived radioactive daughters (decay products), which can attach to airborne particles and contribute to the radiation dose received by individuals in that space. By measuring both radon and its decay products at the same time, the relationship between them can accurately be established, allowing for a precise calculation of the ER.

Other options present information that is not relevant for determining the ER. For instance, temperature measurements or previous indoor radon levels do not impact the immediate calculation of the ratio of radon to its decay products at a given moment. While outdoor air pressure may influence radon levels to some extent, it does not provide the necessary data for the calculation of the equilibrium ratio. Thus, simultaneous measurements of radon and radon decay products are crucial for accurate assessment and