A nationwide survey was conducted in 2014 to investigate environmental outdoor radon level in 33 provincial cities across China. The radon detector used was a passive-type solid-state nuclear track detector, CR-39. Measurements were conducted under the same condition following the quality control programme. Outdoor radon concentrations in China ranged from 3 to 30.0 Bq·m⁻³. The annual arithmetic and geometric mean radon concentration were 14 and 13.2 Bq·m⁻³, respectively. The radon concentrations in the locations near or along coastline were lower than the average value, while those located in the inland area were higher. As a whole, the result showed no big difference from the data measured during the period 1983–1998. It demonstrated that the outdoor radon concentration level in China has not been changing remarkably for 20 years.

The exploitation of mineral resources may cause the environmental release of radionuclides and their introduction in the human trophic chain, affecting public health in the short and long term. A case study of the environmental radiation impact from coal mining and germanium processing was carried out in southwest China. The coal mines contain germanium and uranium and have been exploited for more than 40 years. The farmlands around the site of the coal mining and germanium processing have been contaminated by the solid waste and mine water to some extent since then. Samples of crops were collected from contaminated farmlands in the research area. The research area covers a radius of 5 km, in which there are two coal mines. ²¹⁰Pb and ²¹⁰Po were analyzed as the key radionuclides during the monitoring program. The average activity concentrations of ²¹⁰Pb and ²¹⁰Po in the crops were 1.38 and 1.32 Bq/kg in cereals, 4.07 and 2.19 Bq/kg in leafy vegetables and 1.63 and 1.32 Bq/kg in root vegetables. The annual effective doses due to the ingestion of ²¹⁰Pb and ²¹⁰Po in consumed crops were estimated for adult residents living in the research area. The average annual effective dose was 0.336 mSv/a, the minimum was 0.171 mSv/a and the maximum was 0.948 mSv/a. The results show that the crops grown on contaminated farmland contained an enhanced level of radioactivity concentration. The ingestion doses of local residents in the research area were significantly higher than the average level of 0.112 mSv/a in China, and the world average level of 0.042 mSv/a through ²¹⁰Pb and ²¹⁰Po in crop intake, respectively.

The radiation impact on the environment from naturally-occurring radioactive materials in zircon sand is an important issue for zirconium product manufacturing enterprises. In this paper, a typical oxychloride production enterprise has been taken as an example to study the radiation effect and environmental pollution during the whole production process. The transfer and enrichment of radionuclides in zircon sand was studied by analyzing their concentrations in samples, such as products and wastes, which were sampled from every studied workshop, so that the dose rate in the environment and typical facility surfaces of each workshop could be measured. The study results show that the transfer and enrichment of radionuclides occur mainly in workshops of acidification, dissolution, concentration and crystallization. Silicon slag adsorbed some radionuclides, but most of the radionuclides in raw materials are transferred and enriched in waste acid by the concentration and crystallization process. Sludge and wastewater still contain a large quantity of radionuclides after treatment by wastewater treatment plants. This results in a significant increase in U-238 and Th-232 concentrations in river water near the main outlet. The average effective dose of all employees in the studied enterprises was 0.94 mSv, and workers from the wastewater treatment plants had the largest annual effective dose at 11 mSv.

We report the γ-ray ionizing radiation response of commercial off-the-shelf (COTS) monolithic active-pixel sensors (MAPS) with different integration times and gains. The distribution of the eight-bit two-dimensional matrix of MAPS output frame images was studied for different parameter settings and dose rates. We present the first results of the effects of these parameters on the response of the sensor and establish a linear relationship between the average response signal and radiation dose rate in the high-dose rate range. The results show that the distribution curves can be separated into three ranges. The first range is from 0 to 24, which generates the first significant low signal peak. The second range is from 25 to 250, which shows a smooth gradient change with different integration times, gains, and dose rates. The third range is from 251 to 255, where a final peak appears, which has a relationship with integral time, gain, and dose rate. The mean pixel value shows a linear dependence on the radiation dose rate, albeit with different calibration constants depending on the integration time and gain. Hence, MAPS can be used as a radiation monitoring device with good precision.