Towards a healthy indoor air quality in a school environment -

Abstract

This study targeted the assessment of indoor air quality in a school environment. For this purpose, PM2.5 and CO were monitored in classrooms of forty public and private schools located in urban and rural areas. The field experimental results were coupled with mathematical modeling to estimate the air exchange rate (AER), PM2.5 and CO equivalent emission rates (ER), and PM2.5 deposition and re-suspension rates (DRPM2.5 and RRPM2.5). The field monitoring results showed that elevated PM2.5 levels were prevalent indoors, ranging between 20 and 180 ug-m3 with a mean of 62 ug-m3. Concurrently, outdoor PM2.5 ranged between 20 and 170 ug-m3, with a mean of 50 ug-m3. On the other hand, indoor and outdoor CO concentrations were below threshold values with indoor CO ranging from 1.05 to 6.03 ppm at a mean of 1.62 ppm and outdoor CO ranging from 0.7 to 6.43 ppm at a mean of 1.4 ppm. The corresponding AER ranged between 0.01 and 23.35 h-1 with a mean of 2h-1. In certain schools, higher AERs were associated with high indoor PM2.5 and CO levels due to greater outdoor concentrations. Indoor ERs ranged from 0 to 39.04 mg-h, with a mean of 2.81 mg-h for PM2.5, and from 0 to 157.23 mg-h, with a mean of 7.89 mg-h, for CO. This confirmed the presence of indoor sources such as the usage of chalks and re-suspension of settled particles for PM2.5, and smoking inside schools for CO. Note that PM2.5 DRs varied between 0 and 0.5 h-1 with a mean of 0.1h-1 and were less than the AERs in most classrooms, indicating that the effect of deposition rates on particle removal was negligible compared to the impact of AERs. The study concludes with defining measures towards controlling IAQ in schools.