Indoor radon levels and lung cancer in the Alto Minho region (Northern Portugal): a geological and public health risk assessment.

This study explores the potential association between lung cancer prevalence and geology-derived indoor radon (Rn) concentration potential in Portugal's Alto Minho region. It also considers factors such as the elderly population percentage and the area's geological features. The analysis shows a notable, though variable, association between crude lung cancer rates and geology-derived indoor radon concentration potential across municipalities, reflecting the region's geological diversity. Municipalities classified as having higher indoor radon concentration potential tended to show higher crude lung cancer rates; given the ecological design, this is interpreted as a suggestive association rather than as evidence that radon is an established risk factor in this population. A statistically significant difference was identified between municipalities classified as having 'High' versus 'Low' indoor radon concentration potential-dichotomised using the 300 Bq·m-³ national reference level-in crude lung cancer prevalence (Mann-Whitney U test, p = 0.044). However, this association does not establish causation, as other unmeasured factors, notably smoking and age structure, may be involved. These findings emphasize the importance of continuous radon monitoring and comprehensive epidemiological studies to better understand radon's role in lung cancer and guide effective public health measures in high-radon areas.