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Abstract(s)
A cidade de Lubango, situada no planalto da Huíla, em Angola, é, em termos geológicos,
caraterizada por apresentar rochas maioritariamente graníticas algumas das quais com
alguns vestígios de urânio . Foi, tendo em conta esta realidade e o facto de, tanto quanto se
sabe, não haver estudos desenvolvidos nesta temática, que o grande objetivo deste trabalho
consistiu, principalmente, em se avaliar, a potencial exposição das habitações do Município
do Lubango, no que se refere ao radão, 222Rn, um gás nobre, radioativo, que descende do
rádio, 226Ra, que resulta da desintegração do urânio, 238U, presente em algumas dessas
rochas graníticas.
O gás radão, não é uma ameaça evidente para a saúde, uma vez que a maior parte do radão
inalado, volta a ser expulso após algumas expirações. O perigo iminente associado ao radão
aquando da inalação, reside no facto de este poder sofrer decaimentos radioativos no interior
dos pulmões, dando, desta forma, origem aos seus descendentes por emissão de radiação
alfa. Esses descendentes diretos também podem encontrar-se agregados aos aerossóis que
circulam no ar envolvente e nos epitélios pulmonares e que são os principais contribuintes
pela deposição de energia.
Em geral, os níveis de fundo de radão em espaços abertos, outdoor, são bastante baixos,
cerca de 0,1 a 10 Bq m-3. No entanto, em ambientes fechados, indoor, como é o caso de
hospitais, escolas, residências ou escritórios de instituições públicas, os níveis de radão e
dos seus descendentes podem ser mais elevados, podendo constituir um risco para a saúde
humana. A entrada do radão e a sua acumulação nos espaços habitacionais, pode ocorrer não apenas
devido a fissuras existentes nas fundações, nas paredes e juntas de canalização mal vedadas,
mas, também, a partir de alguns materiais de construção utilizados, que constituem um fator
adicional para o aumento da concentração de radão no interior dos edifícios. As populações
podem ainda ser expostas ao radão e seus descendentes, através da ingestão de água potável
obtida a partir de poços ou outras fontes de abastecimento da população. A maioria do radão
dissolvido na água é rapidamente libertado e dissipado no ar ambiente, no entanto, se existir
em quantidades elevadas, pode contribuir para o aumento da concentração no interior da
habitação e deve ser tomado em consideração. [...]
The city of Lubango, located on the plateau of Huila in Angola, is geologically characterized by the presence of granitic rocks, some of which have traces of uranium. It was, in view of this reality and the fact that, as far as we know, there have been no studies developed on this subject, that the main objective of this work has been to evaluate the potential exposure of the dwellings of the Municipality of Lubango, with regard to radon. Radon is a noble gas, and its isotope 222Rn descends from the radio isotope, 226Ra, which results from the disintegration of uranium, 238U, present in some of these granite rocks. Radon gas is not a clear threat to health, since most radon that is inhaled is expelled again after a few exhalations. The imminent danger associated with radon when inhaled lies in the fact that it can undergo radioactive decay inside the lungs, thus giving rise to its descendants by emitting alpha radiation. These direct descendants can also be found aggregated to aerosols circulating in the surrounding air and in the lung epithelia, which are the main contributors to energy deposition. In general, background levels of radon in open spaces, outdoor, are quite low, around 0.1 to 10 Bq m-3. However, in indoor spaces, such as hospitals, schools, homes or offices of public institutions, levels of radon and its progeny can be higher, and may pose a risk to human health. Radon entry and accumulation in living spaces can occur not only due to cracks in foundations, cracks in walls, poorly sealed pipe joints, but also from some of the construction materials used, which are an additional factor in increasing the concentration of radon inside buildings. Populations can also be exposed to radon and its descendants by drinking water from wells or other sources of water supply. Most radon dissolved in water is readily released and dissolved in ambient air, however, if present in high quantities, it can contribute to increased indoor concentrations and should be taken into consideration. [...]
The city of Lubango, located on the plateau of Huila in Angola, is geologically characterized by the presence of granitic rocks, some of which have traces of uranium. It was, in view of this reality and the fact that, as far as we know, there have been no studies developed on this subject, that the main objective of this work has been to evaluate the potential exposure of the dwellings of the Municipality of Lubango, with regard to radon. Radon is a noble gas, and its isotope 222Rn descends from the radio isotope, 226Ra, which results from the disintegration of uranium, 238U, present in some of these granite rocks. Radon gas is not a clear threat to health, since most radon that is inhaled is expelled again after a few exhalations. The imminent danger associated with radon when inhaled lies in the fact that it can undergo radioactive decay inside the lungs, thus giving rise to its descendants by emitting alpha radiation. These direct descendants can also be found aggregated to aerosols circulating in the surrounding air and in the lung epithelia, which are the main contributors to energy deposition. In general, background levels of radon in open spaces, outdoor, are quite low, around 0.1 to 10 Bq m-3. However, in indoor spaces, such as hospitals, schools, homes or offices of public institutions, levels of radon and its progeny can be higher, and may pose a risk to human health. Radon entry and accumulation in living spaces can occur not only due to cracks in foundations, cracks in walls, poorly sealed pipe joints, but also from some of the construction materials used, which are an additional factor in increasing the concentration of radon inside buildings. Populations can also be exposed to radon and its descendants by drinking water from wells or other sources of water supply. Most radon dissolved in water is readily released and dissolved in ambient air, however, if present in high quantities, it can contribute to increased indoor concentrations and should be taken into consideration. [...]
Description
Keywords
Concentração de radão - Lubango Radão - Dose Anual Efetiva