## 5 Discussion  
The objective of this study was to demonstrate the efficacy of a low-cost IAQ monitoring system in residential settings. The experimental setup yielded valuable insights into the relationships between VOC, CO\({}_{2}\) levels, temperature, and humidity. The employment of data fusion techniques with sensors such as the BME680 and CCS811 enabled the capture of detailed fluctuations in air quality, particularly in response to human activities such as the use of air fresheners and perfumes. The results demonstrate the necessity of monitoring IAQ parameters over time in dynamic, real-life environments, as opposed to controlled laboratory settings where external influences are limited. The considerable discrepancies between the laboratory-derived predictions and the actual real-life data emphasize the intricate nature of residential spaces, where a multitude of factors--including ventilation, occupancy, and material off-gassing--exert a pivotal influence on the determination of air quality.  
Furthermore, the study demonstrated that even minor activities, such as the use of perfumes or essential oil diffusers, can result in considerable short-term elevations in VOC concentrations, which, subsequently, have a detrimental impact on indoor air quality. The observed data demonstrate that while VOC levels eventually return to normal, these sudden spikes may pose health risks, particularly for individuals with pre-existing conditions such as asthma or allergies. The findings emphasize the importance of effective ventilation strategies in residential environments in order to minimize exposure to harmful pollutants. In contrast, spaces such as kitchens and bathrooms, which typically have higher humidity and CO\({}_{2}\) levels, exhibited poorer air quality. This is likely due to the presence of cooking activities and cleaning products, which further underscores the necessity for targeted monitoring in high-risk areas.  
It is acknowledged that air velocity is indeed an important parameter in the study of indoor air quality [56]. Although our study did not specifically measure air velocity, we designed the experiment to minimize its influence by conducting it in a relatively stable environment where air movement was limited. It is proposed by research that air velocities within domestic environments typically range between 0.05 m/s and 0.2 m/s. At lower air velocities (below 0.1 m/s), the impact on pollutant dispersion is typically minimal. In light of the controlled conditions of the experiment, it seems reasonable to posit that any deviations in VOC concentrations due to air velocity were likely to be minor, with a potential variation in readings of less than 5%, as evidenced by findings from similar studies. While the impact of air velocity in our specific experimental setup was minimized, future studies could benefit from incorporating air velocity measurements to further refine the accuracy of IAQ assessments, particularly in more dynamic environments where air movement could have a more pronounced effect on pollutant dispersion.  
The prospective Incorporation of an air quality monitoring system into a smart home environment has the potential to significantly expand its functionality and improve user interaction. By connecting to a central smart home hub, the system will be able to interact with other devices, including HVAC systems, air purifiers, and smart windows. Integration with smart home assistants will facilitate the generation of real-time indoor air quality alerts and queries, allowing residents to more effectively monitor and respond to changes in indoor air quality. Such integration not only improves overall household air quality management but also contributes to a healthier living environment by implementing automated and actionable actions based on real-time data.