title: Hazardous indoor CO2 concentrations in volcanic environments.
abstract: Carbon dioxide is one of the main soil gases released silently and permanently in diffuse degassing areas, both in volcanic and non-volcanic zones. In the volcanic islands of the Azores (Portugal) several villages are located over diffuse degassing areas. Lethal indoor CO2 concentrations (higher than 10 vol %) were measured in a shelter located at Furnas village, inside the caldera of the quiescent Furnas Volcano (S. Miguel Island). Hazardous CO2 concentrations were detected not only underground, but also at the ground floor level. Multivariate regression analysis was applied to the CO2 and environmental time series recorded between April 2008 and March 2010 at Furnas village. The results show that about 30% of the indoor CO2 variation is explained by environmental variables, namely barometric pressure, soil water content and wind speed. The highest indoor CO2 concentrations were recorded during bad weather conditions, characterized by low barometric pressure together with rainfall periods and high wind speed. In addition to the spike-like changes observed on the CO2 time series, long-term oscillations were also identified and appeared to represent seasonal variations. In fact, indoor CO2 concentrations were higher during winter period when compared to the dry summer months. Considering the permanent emission of CO2 in various volcanic regions of the world, CO2 hazard maps are crucial and need to be accounted by the land-use planners and authorities.
authors.affiliation: Centro de Vulcanologia e Avaliação de Riscos Geológicos (CVARG), University of the Azores, Rua Mãe de Deus, 9500-801 Ponta Delgada, Azores, Portugal. Electronic address: Maria.FB.Viveiros@azores.gov.pt.
authors.forename: Fátima
authors.initials: F
authors.lastname: Viveiros
authors.affiliation: Centro de Vulcanologia e Avaliação de Riscos Geológicos (CVARG), University of the Azores, Rua Mãe de Deus, 9500-801 Ponta Delgada, Azores, Portugal.
authors.forename: João L
authors.initials: JL
authors.lastname: Gaspar
authors.affiliation: Centro de Vulcanologia e Avaliação de Riscos Geológicos (CVARG), University of the Azores, Rua Mãe de Deus, 9500-801 Ponta Delgada, Azores, Portugal.
authors.forename: Teresa
authors.initials: T
authors.lastname: Ferreira
authors.affiliation: Centro de Vulcanologia e Avaliação de Riscos Geológicos (CVARG), University of the Azores, Rua Mãe de Deus, 9500-801 Ponta Delgada, Azores, Portugal; Centro de Informação e Vigilância Sismovulcânica dos Açores (CIVISA), University of the Azores, Rua Mãe de Deus, 9500-801 Ponta Delgada, Azores, Portugal.
authors.forename: Catarina
authors.initials: C
authors.lastname: Silva
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D001394:Azores; D002245:Carbon Dioxide / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D015386:Hazardous Substances / Q000032:analysis*; D006798:Housing / Q000592:standards; D011174:Portugal; D012987:Soil / Q000737:chemistry; D018707:Volcanic Eruptions / Q000032:analysis
chemical_list: D015386:Hazardous Substances; D012987:Soil; D002245:Carbon Dioxide
keywords: Carbon dioxide; Human health; Indoor environments; Risk assessment; Volcanic gases