Assessment of environmental γ radiation level and health risk in Changning District, Shanghai

Objective To investigate indoor and outdoor air absorption dose rates of γ radiation in Changning District for the estimation of public exposure doses and the health impacts.

Methods From June to December 2022, using a grid-layout sampling approach, 12 households from each of 10 communities in Changning District were selected based on the construction year, and 15 monitoring points were set for each household. Concurrently, 2 roads and 1 green space were selected as outdoor monitoring points in the center of each community, and a total of 30 outdoor monitoring points were set up. Air dose rates of γ-radiation were measured at each monitoring point using the environment-grade γ dose rate meter. Calculate the annual average effective dose equivalent of environmental gamma radiation for the public, and assess the excess lifetime cancer risk (ELCR) due to environmental gamma radiation.

Results The average values of the absorbed dose rate of γ-radiation in Changning District for indoor and outdoor monitoring points were (125.80 ±11.72) nGy/h and (76.63 ±16.15) nGy/h. Indoor air dose rates of γ-radiation were higher than outdoor rates (P < 0.05). Indoor air dose rates of γ-radiation in households constructed after 2000 were lower compared to those constructed before 2000 (P < 0.05). The annual average of indoor and outdoor effective doses for the public were 0.617 mSv/year and 0.094 mSv/year, respectively. The average excess lifetime cancer risk (ELCR) was 2.56×10^-3 indoors and 4.28×10^-4 outdoors.

Conclusions The air dose rates of γ-radiation in different regions of Changning District varied. The annual average effective dose equivalent and ELCR in Changning District were slightly higher than the global average level and still within the normal fluctuation range nationwide.