Contribution of natural Background radiation to annual effective dose in different areas of Sao Paulo city - preliminary assessment

Abstract

Natural background radiation doses received from some locations in Sao Paulo city, Brazil, were calculated through external gamma radiation levels determined with thermoluminescent dosimeters, assessed quarterly and seasonal during one year. Monitoring stations were placed in 12 different regions of town including both country and urban areas (where building materials are present) and also in the surroundings of the nuclear and radioactive facilities at the Instituto de Pesquisas Energéticas e Nucleares, IPEN. The external exposure due to six months of environmental outdoor gamma radiation levels were compared to the average annual background radiation of IPEN and also with the annual dose limits as proposed by the radiological protection standards.