The effect of seasonal variation on indoor and outdoor carbon monoxide concentrations in Eastern Mediterranean climate

Abstract Monitoring of carbon monoxide (CO) concentration in school microenvironments is extremely important due to its impact on children’s health. CO concentration levels were monitored inside and outside 36 natural ventilated classrooms of 12 schools located in Gaza Strip, Palestine. Measurements were carried out by using electrochemical analyzer during fall, winter, and spring from October 2011 to May 2012. The average concentration of indoor and outdoor CO was 0.79 ± 0.75 and 0.96 ± 0.91 ppm, respectively. The reported concentration levels showed that the indoor CO concentration was lower than the outdoor CO concentration. The mean daily indoor–outdoor ratio ranged between 0.30 and 1.90 in the three seasons. The measured indoor and outdoor CO concentrations showed seasonal variation. During winter, the mean indoor CO was 3.0 and 1.50 times higher than that during fall and spring, respectively. Meanwhile, the outdoor CO concentration in winter was 2.80 and 1.4 times higher than in fall and spring, respectively. Although these levels were below World Health Organization guidelines, these concentrations pose a risk to students’ health and affect their academic performance.