Estimating the Distribution of Lifetime Cumulative Radon Exposures for California Residents: A Brief Summary

Data on residential radon concentrations in California, together with information on California residents' moving histories and time-activity patterns, have been used to estimate the distribution of lifetime cumulative exposures to ²²²Rn. This distribution was constructed using Monte Carlo techniques to simulate the lifetime occupancy histories - and associated radon exposures - of 10,000 California residents. For standard male and female lifespans, the simulation sampled from transition probability matrices representing changes of residence within and between six regions of California, as well as into and out of the other United States, and then sampled from the appropriate regional (or national) distribution of indoor concentrations. The resulting distribution of lifetime cumulative exposures has a significantly narrower relative width than the distribution of California indoor concentrations, with only a small fraction - less than 0.2% - of the population having lifetime exposures equivalent to living their lifetimes in a single home with a radon concentration of 148 Bq.m^-3 or more.