PM2.5 INDOOR/OUTDOOR RELATIONSHIP AND CHEMICAL COMPOSITION IN IONS AND OC/EC IN AN APARTMENT IN THE CENTER OF ATHENS

摘要

The air quality of a residence is influenced by both indoor (i.e. smoking, cooking, cleaning activities etc) and outdoor (vehicles emissions, domestic heating etc) sources. The purpose of the present study is to examine the indoor/ outdoor relationship of PM_(2.5) mass concentration and chemical composition in OC, EC and ions, in an apartment situated on a high-traffic street (Charilaou Trikoupi) in central Athens. The results showed that during the experimental campaign, indoor to outdoor (I/O) ratio ranged between 0.48 and 2.85. However, the ratio exceeded unity only during the two days that smoking took place, indicating the important role of the activity. In the absence of strong indoor sources, indoor and outdoor concentrations are highly -correlated (R~2=0.94), amplifying the assumption that it is the outdoor environment that mainly contributes to indoor PM levels. OC/EC ratios in PM_(2.5) mass ranged from 2.48 to 21.24, averaging 5.16 for the indoor environment and from 1.67 to 3.78, averaging 2.61 for outdoor environment. The average I/O ratio for OC and EC was 1.26 and 0.65, respectively. In addition, regression of indoor versus outdoor concentration of OC and EC, revealed an indoor origin of OC, presumably due to such activities as smoking, cooking and cleaning. Concerning the ionic composition, SO_4~(2-) had a significant contribution to PM_(2.5), for both indoor and outdoor environment. For NO_3~- and NH_4~+, the I/O ratios were much lower than unity (<0.44 and 0.22 respectively), due to the presence of strong outdoor sources (intense vehicles circulation).