Indoor and outdoor particulate matter (PM2.5 and PM10) concentrations in classrooms in Umm Al-Qura University, Makkah, Saudi Arabia

Measurements were carried out to determine the indoor (I), and outdoor (O) mean concentrations of PM2.5, PM10 and their I/O ratios in the presence and absence of students at twenty classrooms located in two different campuses namely Aziziya and Abidyah at Umm Al-Qura University, Makkah city, Saudi Arabia. The levels of both indoor and outdoor particulate matters were higher in classrooms at Aziziya campus than in Abidyah. Average indoor concentrations were comparatively higher than their corresponding outdoor concentrations at both campuses. In Aziziya campus in the presence of students the average levels of indoor of PM2.5 ranged from 72 mu g/m(3) to 178 mu g/m(3) and outdoor ranged from 46 mu g/m(3) to 94 mu g/m(3). For the PM10 was ranged from 49 mu g/m(3) to 150 mu g/m(3) and outdoor ranged from 39 mu g/m(3) to 84 mu g/m(3). In Abidyah campus in the presence of students the average levels of indoor PM2.5 ranged from 38 mu g/m(3) to 58 mu g/m(3) and outdoor ranged from 27 mu g/m(3) to 50 mu g/m(3). For PM10 was ranged from 27 mu g/m(3) to 87 mu g/m(3) and outdoor ranged from 22 mu g/m(3) to 50 mu g/m(3).The corresponding I/O (indoor/outdoor) ratios were ranged from 1.1 to 1.9 for PM2.5, and 1.2 to 1.9 for PM10, in Aziziya campus. In Abidyah campus the I/O ratios were ranged from 1.0 to 1.9 for PM2.5 and from 1.2 to 1.7 for PM10.The frequency percentages distribution of indoor and outdoor revealed that, 65% of the indoor and 45% of the outdoor PM10 concentrations exceeded both the maximum 24-h (50 mu g/m(3)) and the annual mean (50 mu g/m(3)) limits for PM10 set by WHO and EPA, respectively. Regarding PM2.5, 10% (outdoor) of PM2.5 concentrations at all classes in Umm Al university exceeded the maximum 24-h limits for PM2.5 set by WHO. Moreover, 100% of PM2.5 concentrations in indoor and outdoor of all classes in Umm Al Qura university exceeded the annual mean limits for PM2.5 set by WHO. The results of this research can be useful in epidemiological research on students' exposure to PM and in the development and implementation of control actions for the protection of their health.