## 2 Literature Review  
The integration of Internet of Things (IoT) technology into the field of radon monitoring and management has seen a gradual rise, and it holds the potential to transform the way individuals view the associated risks of radon exposure [22]. This change is driven by the deployment of IoT devices for continuous monitoring, as well as the utilization of visual analytics to enhance risk perception, and by the creation of risk management tools suited for the IoT era, such as the Indoor Radon Risk Exposure Indicator (IRREI) proposed by [PERSON] et al. [23; 24]. The advancement of IoT-based system architectures for online radon monitoring and real-time risk management is crucial for improving indoor air quality and building energy efficiency as it enables the integration of sensors, computing, and communication capabilities into cost-effective, small-scale devices [25]. Sensors are placed in buildings to gather data, which is then analyzed, processed, and stored on a central server for continuous monitoring and real-time remediation or preventative measures [26]. There are two main types of radon detection devices: passive and active [27]. Passive devices measure radon gas over a long period, while active devices provide real-time measurements [28]. [PERSON] et al. [29] proposed a cost-effective IoT system for remote radon monitoring. [PERSON] et al. [30] presented the RnProbe, an IoT Edge Device for collecting and transmitting indoor air quality data to the cloud. [PERSON] et al. [31] developed a secure, low-cost system for monitoring and alerting radon levels, with the ability to predict radon levels and take action before reaching the risk level. They later added the capability to control airflow systems based on radon concentration [32]. [PERSON] et al. [33] studied the feasibility of outdoor radon sensors for monitoring volcanic environments. [PERSON] et al. [34] created a cyber-physical system to monitor and control human exposure to ionizing radiation. [PERSON] et al. [35] built an IoT system for real-time radon monitoring, and [PERSON] et al. developed a user-friendly and secure IoT platform for SMEs. [PERSON] designed an IoT system to reduce radon levels in enclosed environments. The study by [PERSON] et al. [32] goes beyond the standard procedures for monitoring radon and provides a more extensive IoT system that can respond to risk mitigation without human intervention, featuring a predictive model to take action before reaching the risk level. The greatest potential of IoT technology lies in the creation of smart and intelligent buildings, where human activity in indoor environments can be managed, leading to new opportunities for savings and improving the occupant experience [36]. IoT devices can be used to enhance a building's energy efficiency, thermal comfort, and IAQ by monitoring a variety of parameters and physically interacting with spaces [37]. For example, these devices can be used to: (i) gather data on which devices or operations consume the most energy, (ii) determine when energy usage is at its highest, (iii) understand how indoor and outdoor activities impact IAQ, and (iv) assess the impact on occupant productivity and health. Some IoT devices can even switch equipment on and off autonomously, such as when detecting inactivity, incorrect temperatures, or high levels of atmospheric pollutants [38]. By extending this resource management to larger areas, such as entire buildings, using programmable and interconnected IoT switches, it becomes possible to optimize and balance resource distribution [39]. The collection and transmission of data from IoT devices to the cloud enable the prediction of trends and patterns in energy consumption IAQ [40]. This technology provides a unique approach to forecasting indoor pollution levels before they reach hazardous levels, allowing for preventative measures to be taken.