Ventilation and particulate levels in dining halls

The dependence of the ventilation on the indoor particulate pollution is highlighted by numerousstudies. The aim of the present study is to examine the influence of the ventilation on the levels of theparticulate concentrations found in dining halls where a large number of students are accommodated. Indoor particulate sources were also quantified.Measurements were conducted in four University dining halls, which are located in different parts ofthe city of Athens. Indoor and outdoor CO2, PM1, PM2,5 and PM10 concentrations along with thenumber of occupants and smokers were measured in each dining hall during the accommodation ofthe students. Measurements were repeated for five working days in each dining hall. Ventilation rateswere estimated by applying a methodology that involves the solution of the mass balance equation for the CO2 concentrations. The indoor particulate production rates were estimated by performingconsecutive numerical experiments with the Multi Chamber Indoor Air Quality Model (MIAQ).Median CO2 concentrations ranged between 1043 ?g m-3 and 1590 ?g m-3 and ventilation ratesranged between 0.58 h-1 and 5.15 h-1. The respective values for PM1 ranged between 8.6 ?g m-3 and 22 ?g m-3, for PM2.5 between 17 ?g m-3 and 60 ?g m-3 and for PM10 between 24 ?g m-3 and 78 ?g m-3.The Pearson correlation coefficient between the log transformed ventilation rates and the PM10concentrations were found to be -0.6. Median values of the total production rates were found to rangebetween 100 ?g min-3 and 5500 ?g min-3 and are highly correlated with the number of occupants(Pearson correlation coefficient 0.86).Examination of the origin of the particulate sources indicated that in the majority of casesresuspension is more significant than combustion sources. Significant short-term variation (one hourtime interval) of the various sources was also observed. Even though the production rates weresignificantly elevated, the measured particulate concentrations were moderate due to the high airchange rates obtained. These findings supports the results of other studies that highlight the significance of ventilation in environments where indoor sources are prominent.