Which unit is used to measure exposure to radon and its decay products?

The unit used to measure exposure to radon and its decay products is "Working Level Months." This unit is particularly significant in the context of occupational exposure and health risk assessments related to radon.

Working Level refers to the presence of radon decay products in the air, specifically the short-lived isotopes that are of concern for lung cancer risk. A Working Level (WL) is defined as a specific concentration of these decay products, which is equivalent to 0.1 Working Level being 100 picocuries per liter (pCi/L) of radon. When assessing radon exposure, it is essential to consider not just the concentration of radon itself, but also the cumulative exposure over time to its decay products.

The term "Working Level Months" combines the concept of exposure (in Working Levels) with time, thus allowing for a more comprehensive assessment of the risk posed by radon decay products over longer periods. This measure is significant for understanding the potential health risks and for setting regulatory standards regarding radon exposure in residential and occupational environments.

In contrast, while microcuries and picocuries are units that measure the activity of radon itself, they do not account for exposure over time or the biological impact of radon decay products