title: Indoor radon periodicities and their physical constraints: a study in the Coimbra region (Central Portugal).
abstract: Indoor radon activities were measured during a period of 6 months, as well as several physical environmental variables (temperature, pressure, humidity and rainfall). The location was a small room at an administrative building of the University of Coimbra, usually undisturbed by human activities and situated over bedrock of low-uranium Triassic red sandstones. A low average activity of radon was observed (36 Bq m(-3)), however showing a very well marked daily periodicity (10+/-5 Bq m(-3)), with maximum values occurring more frequently between 9 and 10 a.m. Daily variations are shown to have no relation with earth tides, and their amplitudes exhibit a significant correlation with outdoor temperature; no dependence on barometric pressure was found. Rainfall disturbs the observed daily radon cycles through a strong reduction of their amplitude, but has no effect on the long-term variability of the gas concentration.
authors.affiliation: IMAR, Department of Earth Sciences, University of Coimbra, 2 Coimbra, Portugal. luisneves@dct.uc.pt
authors.forename: L J P F
authors.initials: LJ
authors.lastname: Neves
authors.forename: S M
authors.initials: SM
authors.lastname: Barbosa
authors.forename: A J S C
authors.initials: AJ
authors.lastname: Pereira
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis* / Q000706:statistics & numerical data; D005843:Geography; D007700:Kinetics; D010507:Periodicity; D011174:Portugal; D011834:Radiation Monitoring; D011886:Radon / Q000032:analysis*; D013997:Time Factors
chemical_list: D000396:Air Pollutants, Radioactive; D011886:Radon