Objective To systematically assess radon concentrations and environmental terrestrial gamma-radiation doses in subway stations of Shanghai.
Methods From August to December 2009, 73 stations were selected randomly from 98 stations of Shanghai subway lines, including Line 1, Line 2, Line 4, Line 6, Line 8 and Line 9, which involved underground sections. Instantaneous radon concentrations were measured with AB-4 radon gas monitor, and environmental terrestrial gammaradiation dose rates were obtained with FD-3013H intelligent X/γ radiometer.
Results The radon concentrations were in the range of 1.2-28.4 Bq/m3, with the average of 9.9 Bq/m3, which were significantly lower than the national standard. The environmental terrestrial gamma-radiation dose rates were in the range of 0.07-0.24 μSv/h, and the average was (0.14& #177;0.02) μSv/h, within the fluctuations of natural background radiation.
Conclusion The radiation level in Shanghai subway stations is within natural background levels, and the radon concentration is obviously below admissible dosage.
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