## 1 Introduction  
Radon (\({}^{222}\)Rn) is a naturally occurring radioactive element, which is part of the progeny of Uranium (\({}^{238}\)U) [1]. Since it is the only element of this progeny that occurs in the gaseous state, Rn emission is particularly important given the risk of inhalation in indoor environments, completing its decay process inside the lungs. Given the Rn half-life of 3.8 days, the continuous release of alpha particles may reach the alveolar epithelium lung cells, which can cause damage and injuries from continuous exposure [2, 3, 4, 5, 6, 7]. Hence, Rn exposure may lead to oncological problems according to the World Health Organization (WHO) classification, which ranks Rn as the second cause of lung cancer after tobacco smoking and the first cause among non-smokers [8, 9, 10, 11]. In order to evaluate indoor Rn exposure, it is not only important to assess indoor Rn concentration but also to evaluate the mechanisms that contribute to its increase along with the variation over time, together with possible relationships with other factors, such as meteorological factors (temperature, relative humidity, and atmospheric pressure) or factors associated with geology (soil properties, such as permeability, uranium content in soils and rocks, fracture in the land formed by rocky massfits, state of alteration, and water content, among others). The analysis of the problem as a whole, including all variables that may contribute to indoor Rn exposure evaluation, assumes a fundamental role in the future implementation of remediation measures [12; 13; 14; 15; 16].  
The adoption of remediation measures should help not only to reduce indoor Rn exposure but also to keep indoor Rn concentration levels below a value considered safe, according to the European regulation of 300 Bq\(\cdot\)m\({}^{-3}\). Although, there are studies that point to an increased risk from concentrations of 50 Bq\(\cdot\)m\({}^{-3}\) onwards. It is widely reported that rooms with low indoor Rn concentrations may allow for the safe and secure use of a building by ensuring that users are not exposed to high-risk levels [8; 17; 18]. However, the concerns of building managers nowadays are not only focused on issues related to a room's Indoor Air Quality (IAQ) since the adoption of sufficiently high ventilation rates in indoor rooms seems to be enough, for most cases, to solve problems related to a high concentration of the most polluting agents, in which Rn is included [19]. More recently, issues related to energy efficiency play a decisive role in building management, and the use of high air renovation rates to tackle IAQ problems may lead to significant heat losses that notably affect the users' thermal comfort in the winter season. Therefore, the balance between ventilation habits and the energy efficiency requirements to promote users' thermal comfort is of utmost importance [20; 21].  
Given these conditions, the present study aims to analyze the variation in indoor Rn concentration over an extended period to determine the presence of a broad-spectrum seasonal fluctuation potentially related to meteorological factors. By utilizing a LoRa-enabled IoT edge device to collect data, the continuous acquisition of indoor Rn concentration as well as indoor air temperature, relative humidity, and atmospheric pressure allows us to assess the seasonality potential of Rn emission and its correlation with meteorological factors. This analysis fosters the development of more precise procedures for indoor radon mitigation, taking into account not only the seasonality in Rn emission but also the building's energy efficiency and its impact on the thermal comfort of the building occupants. This approach can be extended to other scenarios involving indoor gas emissions, as seasonal patterns should exhibit tendencies related to the propagation of other air pollutants.