Indoor radon concentration survey in Mexico

Indoor radon evaluations in specific regions of the country have been performed in an effort to assess the magnitude of the radon problem and its public health consequences. The survey of this paper covers four large non-tropical regions of north and central Mexico, and reports the results of measurements of indoor radon concentrations in houses of towns with between 100,001 and 500,000 inhabitants. The measurements were done by using passive detectors, namely, the closed-end-cup system with CR-39 polycarbonate chips as detector material. The measurements were performed throughout the two coldest seasons (between 5 and 20°C), winter and spring, in integration periods of 28 days covering the six month cycle. The results show a moderate average radon concentration below 200 Bq·m⁻³ with occasional higher values. This is very probably due to the climate conditions and the traditional habits of open door and window ventilation. The IFUNAM (Instituto de Física, Universidad Nacional Autónoma de México) Laboratory, where the closed-end cup system for radon was developed, has gained experience though this survey and is willing to share it for future surveys at regional or national levels.