What is the formula for calculating Working Level Months (WLM)?

The formula for calculating Working Level Months (WLM) is WLM = WL x hours of exposure / 170. This formula is derived from the relationship between working level (WL), exposure time, and the concept of radiation exposure over a period. In the context of radon measurement, working levels represent the concentration of radon decay products, while WLM provides a way to quantify cumulative exposure over time.

The factor of 170 in the denominator is significant because it standardizes the measurement, allowing for a consistent way to express radon exposure from various environmental or occupational scenarios. This factor reflects the average exposure level that can lead to adverse health effects over time. Therefore, when determining potential health risks associated with radon exposure, the ratio of working level to exposure time is essential.

Using this specific number ensures that the calculated WLM corresponds accurately to the risk of developing conditions linked to radon exposure, such as lung cancer. The different numbers in the other choices do not align with established guidelines or scientific consensus regarding radon exposure, making the correct answer crucial for accurate risk assessment in environments where radon is present.