Detecting extremely low light signals is the basis of many scientific experiments and measurement techniques. For many years, a high-voltage photomultiplier has been the only practical device used in the visible and infrared spectral range. However, such a solution is subject to several inconveniences, including high production costs, the requirements of a supply voltage of several hundred volts, and a high susceptibility to mechanical damage. This paper presents two detection systems based on avalanche photodiodes, one cooled and the second operating at room temperature, in terms of their potential application in thermoluminescent dosimeter units. The results show that the detection system with an uncooled photodiode may successfully replace the photomultiplier tube commonly used in practice.

Radon is one of the leading causes of lung cancer worldwide. Following the implementation of the European Council Directive 2013/59/EURATOM, regular measurements of radon concentrations in workplaces have been carried out in European countries for approximately ten years. This provides a basis for assessing the exposure of workers and the general population to radon, as well as for determining the need to implement measures aimed at reducing this exposure. In addition to commonly used methods that focus on eliminating radon sources or minimizing its ingress into buildings, there are also temporary measures available, such as using air purifiers to improve indoor air quality. Although they are not recommended as a standalone or definitive solution, they can be useful as an interim measure—until appropriate actions to reduce indoor radon concentrations are implemented. In this study, five commercially available air purifiers were tested under controlled laboratory conditions to assess their impact on radon and its decay products. The results show that none of the tested devices significantly reduced gaseous radon concentrations. However, the air purifiers were highly effective in removing radon progeny, achieving a 95–99% reduction in potential alpha energy concentration (PAEC) and reducing the equilibrium factor from 48 to 76% to 0–2%. From a sustainability perspective, these findings are relevant for public health protection, responsible consumer decision-making, and evidence-based indoor air quality management. By distinguishing between ineffective radon gas removal and effective reduction of dose-relevant decay products, this study supports sustainable risk mitigation strategies and helps prevent the misuse of energy- and resource-intensive technologies for purposes they cannot fulfill.

Radon (²²²Rn) is a naturally occurring radioactive noble gas that is a major source of ionising radiation in the environment. Many measurement techniques can be used to monitor ²²²Rn concentrations in the workplace. The main purpose of conducting such measurements is to identify locations of exposure, determine the effective dose for workers and, if necessary, define actions for reducing the exposure. As part of this study, a series of measurements were conducted in the underground tourist route at Książ Castle in Poland. The route has been open to visitors since late 2018. The measurements included long- and short-term tests. Passive and active methods were used to measure the ²²²Rn activity concentration. Additionally, the potential alpha energy concentration and ambient and radioactive aerosol size distributions were measured. Finally, the annual effective dose for workers was estimated. The dose was calculated while factoring in the legal regulations in the Czech Republic and Poland to demonstrate their effect on the final results. The obtained values were low—they did not exceed 0.218 mSv (for the specified exposure time)—indicating the effectiveness of natural ventilation and a low radiation risk to personnel.