## 3 Analysis of the Variation of the Air Quality in the Different Living Rooms of a Single Building
The highest concentrations of VOC are observed in the bathroom, primarily attributed to the presence and use of air fresheners, cleaning products, cosmetics, and personal care items [44]. These sources emit a variety of VOC into the air, contributing to elevated levels within the confined space of the bathroom. Figure 8: Dataset for volatile organic compounds. In the kitchen, the levels of VOC are influenced by the cooking activities that take place there and the operation of air heaters, both of which can release VOCs into the indoor environment. Cooking processes, including frying, baking, and grilling, produce combustion byproducts and cooking emissions, which further contribute to the VOC load in the kitchen air. Additionally, the operation of gas appliances and the use of certain cooking materials may also contribute to VOC emissions. Conversely, in the bedroom, sources of VOC are minimal compared to those in the kitchen and bathroom. While personal care products and cleaning agents may still contribute to VOC emissions to some extent, their impact is typically lower in this space. As a result, VOC concentrations in the bedroom are generally lower compared to the other living spaces examined. In order to provide a comprehensive background for our indoor air quality assessments, we conducted outdoor measurements for temperature and humidity over a period of 10 days. These measurements serve as a reference to better understand the dynamics of the indoor environment. The inclusion of outdoor temperature and humidity data, presented alongside the existing indoor IAQ indexes, enables a more nuanced analysis by accounting for external influences. This approach helps to contextualize the indoor air quality data, offering a clearer understanding of the factors affecting indoor environmental conditions. The accompanying images illustrate the outdoor temperature and humidity trends, providing essential background information for our study. Figure 9 presents the outdoor temperature and Figure 10 shows the outdoor humidity. Figure 11 illustrates the fluctuations in CO\({}_{2}\), VOC levels, and IAQ index throughout the day, from 8:00 to 22:00. This visualization offers a comprehensive overview of the fluctuations in concentrations of volatile organic compounds and their corresponding impact on indoor air quality over the course of the day. The illustration demonstrates the relatively stable behavior of the IAQ index and VOC levels throughout the day, with IAQ remaining within the range of 50-65 and VOC concentrations between 15 and 20. These stable levels indicate that, despite the occurrence of daily indoor activities, there were no notable increases in pollutant sources such as cleaning products, cooking, or aerosols that typically elevate VOC levels. Similarly, the IAQ index, which is influenced by a combination of CO\({}_{2}\), VOC, and other factors, demonstrates minimal variation, indicating that the indoor air quality remained moderate without significant deterioration throughout the day. However, the CO\({}_{2}\) concentration demonstrates a consistent upward trajectory, rising from 460 ppm at 08:00 to 620 ppm by 22:00. This increase can be attributed to the gradual accumulation of exhaled CO\({}_{2}\) from occupants in the enclosed environment, combined with potentially limited ventilation throughout the day. The uninterrupted increase in CO\({}_{2}\) levels, without parallel rises in VOC or IAQ values, underscores the influence of human activity, particularly respiration, on indoor air quality. This trend in CO\({}_{2}\) emphasizes the necessity for effective ventilation in order to prevent the accumulation of carbon dioxide in residential spaces, particularly in situations where IAQ and VOC levels may remain constant but CO\({}_{2}\) rises due to inadequate air circulation. Prolonged exposure to elevated CO\({}_{2}\) concentrations can result in discomfort and a reduction in cognitive function, making it a crucial parameter to monitor and address.