VARIATIONS IN NATURAL BACKGROUND-RADIATION ACROSS CANADA

This paper describes gamma radiation levels from across Canada obtaine d with a network of thermoluminescent dosimeters (TLDs) at 28 environm ental monitoring sites and 5 nuclear generating stations. The results showed clear trends with geographical location. Generally, readings fr om the prairie provinces (Alberta, Saskatchewan, and Manitoba) were hi gher than average, whereas readings from central Canada (Ontario and Q uebec) were lower. There were no significant seasonal variations. The levels around the nuclear generating stations were not significantly d ifferent from those at the environmental monitoring sites. The nationa l average of the gamma dose rate was 76 nGy h(-1), with a standard dev iation of about 10 nGy h(-1). This variability has implication for a d e minimis radiation dose and for possible epidemiological studies of t he effects of low level radiation. Copyright (C) 1996 Elsevier Science Ltd.