## 5 Conclusions  
This systematic review of 70 studies provides comprehensive evidence of the evolution in IEQ monitoring approaches in school classrooms following the COVID-19 pandemic. The findings demonstrate significant advancements in measurement methodologies and understanding of parameter interactions, with several key conclusions:  
* Thermal comfort and indoor air quality (IAQ) correlations: A notable positive correlation between thermal comfort and indoor air quality was identified. This suggests that improving ventilation and maintaining appropriate thermal conditions may contribute significantly to overall indoor environmental quality.
* Ventilation-acoustic relationships: the analysis revealed weak correlations between ventilation and acoustic comfort, suggesting that while ventilation is crucial for maintaining air quality, it does not strongly impact noise levels in classrooms. Acoustic treatment may be needed separately to ensure an optimal learning environment.
* Lighting interactions: light levels were found to have a modest negative correlation with relative humidity and air velocity, indicating that changes in lighting could potentially affect the perception of air quality in classrooms. Further studies may be required to explore these interactions in greater detail.
* Post-COVID-19 modifications: a significant shift toward enhanced filtration systems, with MERV-13+ filters being utilized in 86% of the studies, reflects the growing concern about indoor air quality post-COVID-19. This emphasizes the importance of clean air as a priority in maintaining health and safety within educational environments.
* Advances in measurement strategies: there has been a notable evolution in measurement techniques, with real-time monitoring (57.4% of studies) and remote monitoring capabilities (68.9% of studies) becoming standard practices. These technologies allow for the continuous tracking of environmental conditions and enable timely adjustments to enhance IEQ.
* Multi-parameter integration: the integration of multiple parameters (32.8% of studies) has become more common, recognizing the interconnected nature of indoor environmental factors. This approach allows for a more holistic understanding of how variables like temperature, humidity, ventilation, and lighting interact and affect occupants' experience.  
**Author Contributions:** Conceptualization, S.D.L.; methodology, S.D.L.; software, S.D.L.; validation, S.D.L., M.F. and M.P.; formal analysis, S.D.L.; investigation, S.D.L.; resources, S.D.L.; data curation, S.D.L. and M.P.; writing--original draft preparation, S.D.L. and M.F.; writing--review and editing, S.D.L.; visualization, S.D.L.; supervision, S.M.; project administration, S.M.; funding acquisition, S.M. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the project \"necessARIA--Need for efficient strategies of air exchange for health of occupants in school buildings\" (PNC--National Plan complementary to the PNRR; PNC Ministry of Health; E.1 Health-environment-biodiversity-climate) by the Ministry of Health.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data are contained within the article.  
**Conflicts of Interest:** The authors declare no conflicts of interest.