Changes in per capita and collective dose equivalent due to natural radiation in Taiwan (1950-1983)

This paper deals with the changes in per capita and collective dose equivalent in Taiwan in the past three decades based on the measured terrestrial and cosmic radiation levels and the population distribution as well. Over 70% of the population is concentrated in three population centers which have been naturally formed in the north, middle and south of Taiwan along the west coast as a result of industrialization and population growth. The population has increased 2.5 times in the past 33 y and reached to 1.9 X 10(7) persons, yet the migration of population was from the rural areas where the natural radiation is usually high to the urban areas where the natural radiation is usually low. The resulting collective dose equivalent has been increasing, yet the per capita dose equivalent, on the contrary, has been decreasing.