Diurnal variations in radon concentrations in a school and office: : implications for determining radon exposure in day-use buildings

Diurnal radon concentrations were measured in a school and an office that exhibited high average annual radon concentrations from passive alpha track detector measurements. The diurnal measurements in both cases showed very high nighttime concentrations (3000–6000 Bq m−3) and low daytime concentrations under the action level of 200 Bq m−3 used in Norway. These results suggest that the only way to accurately assess radon exposure in day-use buildings is to include measurements of radon concentrations limited to the hours when the buildings are actually in use.