Investigation of environmental natural penetrating radiation level in Shanghai city

The methods and results of the investigation on natural penetrating radiation level in Shanghai city from 1987 to 1988 are presented. 178 measuring points of 1.5 x 1.5 km-grid in the urban areas and 253 measuring points of 5 x 5 km-grid in suburban areas were set up uniformly. The results show that: (1) The point-weighted average values of natural γ radiation dose rate for field, road and inside buildings are 5.45, 5.99 and 9.70 x 10-8 Gy·h-1, for which the population-weighted average values are 5.49, 6.72 and 9.69 x 10-8 Gy·h-1 respectively; (2) the population-weighted average values of the dose rate indoor and outdoor from cosmic ray are 2.47 and 2.88 x 10-8 Gy·h-1, respectively; (3) the annual effective dose equivalents from natural γ radiation, cosmic ray and natural penetrating radiation are 0.54, 0.25 and 0.76 mSv respectively, and correspondingly, the annual collective effective dose equivalents are 0.39, 0.54 and 0.93 x 104 man·Sv respectively