Radon risk analysis in a set of public buildings in Minho region, Portugal: from short-term monitoring to radon risk assessment

Abstract

The World Health Organization (WHO) considers radon gas as one of the most important agents responsible for lung cancer. Hence, radon people exposure in badly ventilated and extensively occupied rooms increases drastically the risk of health problems. Since new legislation is already in force in Portugal to combat radon risk problems, the discussion of a mitigation strategy to reduce occupants’ radon risk exposure is an issue of big actuality, of greater urgency and of extreme necessity.An administrative building made with granite stonework and founded over granite rocks, located in an inner city of Minho region, North of Portugal, was extensively assessed to characterize indoor radon concentration, air temperature and relative humidity in two office rooms, a ground floor and a top floor room. The ground floor office has numerous occupants during large periods, and the radon risk analysis showed hazard concerning radon gas exposure. The experimental assessment involved the use of short-term measurements of one complete week, over winter and summer seasons.The Indoor Effective Dose (IED) calculation, considering a dosimetric approach for the room occupation schedule, allowed concluding that during all working day, the office was above the occupational dose limit of 1 mSv/year, prescribed by the International Commission on Radiological Protection (ICRP). According to results, there is evidence that the occupants’ radon risk exposure is very high, wherefore some remediation measures are mandatory. The room mitigation actions should necessarily involve a set of technical solutions to reduce the potential risk for occupants combined with some awareness-raising activities to alert for risk occupation during large periods. Thus, a radon mitigation strategy is obligatory in order to provide occupants´ protection.