It is important to evaluate environmental gamma-ray exposure both at work and home in order to assess people's collective dosages. Environmental gamma radiation was measured for air-absorbed dose with a thermoluminescence dosemeter at various points in the workplace and Ningyoutouge, and workplace radiation characteristics were analysed. From the results, the public dose due to gamma rays generated artificially was assessed to be sufficiently lower than the annual limit. For indoor environments of the workplace, the maximum dosage rate among measured values was 97nGy/h and the minimum value was 70nGy/h, the average over one year was 83nGy/h. The average annual outdoor dosage for a year was 82nGy/h. In Ningyotoge, the maximum was 103nGy/h, minimum 60nGy/h, and average 88nGy/h. These values depend on the nature of the soil and weather factors, showing higher values in the summer than in the winter in the workplace. There was no significant difference in the dosage rate in houses and the workplace.
A preliminary survey of the gamma-ray exposure rate was carried out at Guarapari and Meaipe in Brazil in September 1998. In those areas, exposure rates in the streets ranged from 0.1 to 0.4μGy/h except for a few places such as near the beaches. Exposure rates inside houses were lower than 0.2μGy/h except for two houses where an exposure rate of 0.4μGy/h was measured. Our effective dose rate from external terrestrial irradiation was 0.17μSv/h on the average during the period of our three-day stay in Guarapari (outdoors and indoors). These values are lower than those observed in the 1960s, which were cited in UNSCEAR reports. This fact suggests that the natural radiation environment of Guarapari has varied with urbanization, which brought paved streets, and changes in the structure and building materials of houses. A detailed survey is necessary in order to evaluate the present exposure rates in these areas.