Abstract
Classroom indoor air quality (IAQ) can contribute to students' wellbeing, academic performance, and quality of life. While classroom IAQ field assessments are regularly conducted globally, they are limited in the Kingdom of Saudi Arabia (KSA). Initiatives driven by Saudi Vision 2030 point toward improving IAQ conditions in classrooms and lead to the development of enhanced pilot school models. This study assesses classroom IAQ in conventional and pilot secondary public schools in Jeddah using CO2 concentration levels as a commonly used indicator for comparing IAQ and ventilation performance. CO2 levels were measured in 12 classrooms (N = 12) that used different mechanical conditioning systems in three schools. The results revealed that all the examined classrooms reported high levels of CO2 concentrations in excess of the recommended 1,000 ppm by ANSI/ASHRAE Standard 62.1, which was mainly due to classrooms being overcrowded, the type of mechanical conditioning system, and students' behavioral patterns and operational schedules. More practical guidance on the provision of fresh air and the efficiency of mechanical ventilation systems is required to ensure adequate ventilation and pollutant dilution.