Resumen
The effective doses received by the general population from the natural radioactivity in the city of São Paulo, Brazil, were assessed from 2007 to 2013, as, apart from the variation from place to place, the background gamma levels in air are not constant in time. The outdoor gamma radiation levels were carried out with thermoluminescent dosimeters, TL, quarterly exposed, using twelve monitoring stations, covering both places frequented daily by people with emphasis in the most populated districts and outskirts areas, with no influences from man-made ionizing radiation sources. The average annual effective dose in the city of São Paulo, found as 1.3 ± 0.1 mSv, is below the annual global per caput effective dose due to natural radiation sources of 2.4 mSv and within the annual effective doses range of 1 to 3 mSv, expected to be received by 65% of major population.