# Influence of Particulate Matter and Carbon Dioxide on Students' Emotions in a Smart Classroom
## 4 Discussion  
The aim of this study was to explore the impact of environmental factors, specifically CO\({}_{2}\) and PM, on students' emotions in classroom. Previous research suggested that air quality can significantly affect cognitive, health, and emotion dimensions, with poorer air quality often linked to health problems, less performance, and negative affect. By using regression models and correlation analyses, our study quantify the influence of various pollutants, including PM\({}_{1}\), PM\({}_{2.5}\), PM\({}_{10}\), and CO\({}_{2}\), on emotions such as anger, fear, sadness, happiness, disgust, and neutral. The results revealed significant but weak correlations between levels of CO\({}_{2}\) and various emotions, particularly those with negative connotations. Positive associations were found between CO\({}_{2}\) and emotions such as anger (rho = 0.098, \(p\) < 0.001), disgust (rho = 0.078, \(p\) < 0.001), and sadness (rho = \(-\)0.051, \(p\) < 0.001). These correlations suggest that higher levels of CO\({}_{2}\) may be associated with an increase in negative emotions. These findings are partially consistent with previous research, particularly regarding the link between CO\({}_{2}\) and negative emotions. Although there was no positive Spearman correlation between CO\({}_{2}\) and fear, the regression model coefficient did reveal a small but significant coefficient with fear. This supports the idea that an increase in CO\({}_{2}\) could be related to a rise in fear levels, which is consistent with the literature [24]. Beyond the effects of CO\({}_{2}\), our study also revealed significant associations between PM and various emotions. For example, PM\({}_{2.5}\) showed a weak but significant correlation with emotions such as anger (rho = 0.016, \(p\) = 0.006), disgust (rho = 0.023, \(p\) < 0.001), and fear (rho = 0.017, \(p\) = 0.003), while PM\({}_{10}\) was similarly associated with disgust (rho = 0.029, \(p\) < 0.001) and fear (rho = 0.014, \(p\) = 0.015). These findings align with the existing literature indicating the significant impact of indoor PM, particularly PM\({}_{2.5}\), on emotional well-being. Studies such as [25; 26] demonstrated that increases in PM\({}_{2.5}\) levels are correlated with negative emotional responses, such as those observed in social media posts. Similarly, Ref. [27] analysis of PM\({}_{10}\) highlighted a relationship between increased PM levels and negative public sentiment, supporting our findings. In addition, Ref. [30] research emphasizes how emotional health can modulate the effects of air pollution, showing that individuals who are less happy are more vulnerable to its adverse impacts. This may explain the variability in emotional responses to environ  
Figure 4: Standardized regression coefficients for each emotion. mental factors observed in our study, where more negative emotions were correlated with higher particulate matter levels. Regarding the regression models, we observed a pattern in neutral emotion. The initial increase in PM\({}_{10}\) raises the likelihood of neutral emotion, potentially indicating a decrease in the intensity or frequency of other emotions. Neutral emotion may prevail when other basic emotions are not expressed. Although this observation is not definitive, it suggests that higher particulate matter levels could reduce the cognitive and emotional arousal necessary to trigger stronger emotional reactions. This aligns with previous studies that have shown poor air quality, particularly elevated PM and CO\({}_{2}\) levels, to be associated with reduced cognitive performance and emotional engagement [19; 20; 21]. As cognitive and emotional responses diminish, neutral emotional states might become more prevalent. However, further research is needed to fully explore the mechanisms behind this relationship.