Seasonal Variation of Indoor Rn at a Location in the Southwestern United States

Abstract

Radon-222 concentrations have been measured in 12 homes typical of a small town in the southwestern United States. Nine of the houses, in which both summer and winter data are available, have an annual mean of 63 +/- 18 Bq m-3 (1.7 +/- 0.5 pCi L-1) and a range of 41 to 96 Bq m-3 (1.1 to 2.6 pCi L-1). These results were obtained with passive Rn dosimeters using polycarbonate nuclear track detector foils. The overall results fall slightly above the middle of the range of values obtained in other studies in the United States. Winter levels clearly exceed summer by a factor of from two to three. This result is attributed primarily to wide use of evaporative air conditioners for daytime cooling in the summer together with the fact that doors and windows are left open frequently during evening and nighttime hours. Both practices enhance the exchange of outdoor air with indoor air contributing to a decrease in the indoor Rn levels during the summer season. Room-to-room differences were evident during the winter season only. Bedrooms and bathrooms were generally higher in Rn than kitchens and living rooms but by only about 25%. The two adobe houses in the group showed higher Rn concentrations during the winter season than did those of frame-stucco, concrete, or cinder block construction. Dose equivalent calculations yielded a mean figure of 0.29 WLM y-1 for typical occupancy patterns in these New Mexico houses.

The influence of season, bedrock, overburden, and house construction on airborne levels of radon in Maine homes

“…In other studies, average air radon measurements in the winter have been higher than summer measurements (Cohen and Gromicko, 1988;Hess and others, 1985;Mushrush and Mose, 1988;Wilkening and Wicke, 1986). In our study, season of the year did not show a significant association with air radon using a nonparametric test; however, the logistic regression, multivariate model, showed winter measurements to be nearly three times more likely to be 4 pCi/L or above than summer measurements.…”

“…The strong seasonal effect may be due to frost retarding the migration of radon through the soil to the atmosphere (Nazaroff and others, 1988), coupled with the pressure gradient created by the temperature differences between the inside and the outside of the house (the "stack effect"), which draws radon out of the soil (Buchli and Burkart, 1989;Wilkening and Wicke, 1986).…”

“…These include the construction of the house (George and Breslin, 1980;Radford, 1985), the construction of the basement (Mushrush and Mose, 1988;Centers for Disease Control, 1989;Buchli and Burkart, 1989), the draftiness of the house (Hess and others, 1985;Cohen and Gromicko, 1988), and the season of the year (Wilkening and Wicke, 1986;Mushrush and Mose, 1988;Hess and others, 1985).…”

Variability of radon and thoron concentration with type of dwellings in a hilly area

“…This leads to a mixing of indoor air well with the external environment resulting in lower concentrations of indoor radon, thoron and its progeny. 17,34 Radon and thoron concentrations in an enclosed environment are affected by the degree of exchange with outdoor air as measured by the ventilation. 23 The magnitude of seasonal variation of radon and thoron concentrations is pronounced well by the ratios of its concentrations observed during various seasons.…”

Long-term radon investigation in four selected kindergartens in different geological and climate regions of Slovenia

“…4 Various factors, such as geological characteristics and uranium content in the soil, building materials, quality of the building construction, climate and living habits (ventilation rate) all influence the indoor radon concentration, which varies seasonally, monthly and daily. 5,6 According to a country's particular characteristics the contribution of a singular parameter may be very different. Therefore a long-term study in a small number of the Slovenian kindergartens was performed, to obtain more information how local geology, climate and building material, and occupational patterns affect radon concentration in a kindergarten.…”