Indoor and outdoor PM concentrations at a residential environment, in the Athens area

摘要: The aim of the present work was to study exposure to PM in the indoor and outdoor microenvironment of a typical residence in the center of Athens. Simultaneous indoor and outdoor measurements of PM10 and PM2. 5 were conducted, by the use of gravimetric and continuous samples, during October and November 2006. Moreover, air exchange rate was monitored continuously during the entire measurement period. The indoor and outdoor concentration levels were significant for both size fractions. Mean daily PM10 outdoor concentrations exceeded the EU 24-hr limit value for 84% of the measured days, while the respective PM2. 5 concentrations exceeded the 24-hr limit value set by the CAFE working group for 69% of the measured days. PM10 and PM2. 5 concentrations exhibited increased short-term variability with high peak concentrations during morning and afternoon/night rush hours.Indoor concentration levels seem to be mainly affected by PM of outdoor origin, since the calculated indoor-to-outdoor concentrations ratios (I/O) were much lower than 1.00 during all days and indoor and outdoor concentrations were highly correlated. This finding was also supported by the pattern of their diurnal cycles, which followed the outdoor ones, with a delay of approximately 1 hr.