Radon in indoor air of primary schools: determinant factors, their variability and effective dose

Abstract

Radon is a radioactive gas, abundant in granitic areas, such as in the city of Porto at the north-east of Portugal. This gas is a recognized carcinogenic agent, being appointed by the World Health Organization as the leading cause of lung cancer after smoking. The aim of this preliminary survey was to determine indoor radon concentrations in public primary schools, to analyse the main factors influencing their indoor concentration levels and to estimate the effective dose in students and teachers in primary schools. Radon concentrations were measured in 45 classrooms from 13 public primary schools located in Porto, using CR-39 passive radon detectors for about 2-month period. In all schools, radon concentrations ranged from 56 to 889 Bq/m(3) (mean = 197 Bq/m(3)). The results showed that the limit of 100 Bq/m(3) established by WHO IAQ guidelines was exceeded in 92 % of the measurements, as well as 8 % of the measurements exceeded the limit of 400 Bq/m(3) established by the national legislation. Moreover, the mean annual effective dose was calculated as 1.25 mSv/y (ranging between 0.58 and 3.07 mSv/y), which is below the action level (3-10 mSv). The considerable variability of radon concentration observed between and within floors indicates a need to monitor concentrations in several rooms for each floor. A single radon detector for each room can be used, provided that the measurement error is considerably lower than variability of radon concentration between rooms. The results of the present survey will provide useful baseline data for adopting safety measures and dealing effectively with radiation emergencies. In particular, radon remediation techniques should be used in buildings located in the highest radon risk areas of Portugal. The results obtained in the current study concerning radon levels and their variations will be useful to optimize the design of future research surveys.

Indoor radon measurements in residential dwellings in Qom, Iran

“…According to the previous studies, the average amount of radon in Qom dwellings is higher than that in the cities of Gorgan, Shiraz and Mashhad and lower than that in the other cities of Iran mentioned in table 4. The higher amount of radon has been reported in some regions of Cameroon (1) , Italy (37) , and Portugal (10) . The highest and lowest radon concentrations are observed on basement and second and upper *loors (higher than 1 st *loors) equaling 123.43 and 40.69 Bq m -3 respectively.…”

“…World Health Organization (WHO) proposes a reference level of 100 Bq m -3 to minimize health hazards due to indoor radon exposure. However, if this level cannot be reached, the chosen reference level should not exceed 300 Bq m -3 (10,11) .…”

Indoor radon levels and total gamma dose rates measurements in Portuguese thermal spas

“…In most thermal establishments the highest indoor radon concentrations were obtained during the winter period, which is consistent with the literature (Ziane et al, 2014) consulted and other studies developed, in which the indoor radon concentration in autumn/winter is higher than the radon concentration in indoor air in spring/summer. The considerable variability of the radon concentration observed in each thermal establishment is influenced by many factors, namely: rock type, double glazing, window opening habits, building materials used in the walls, type of flooring and draught proofing (Madureira et al, 2016).…”

Assessment of indoor radon levels in Portuguese thermal spas

“…Also, the laboratory takes part regularly in inter-comparison exercises with other laboratories in order to estimate the statistical uncertainty (analytical error less than 10% of the obtained value). The detection limit using the procedure described is 5 Bq m −3 (Madureira et al, 2016).…”