Indoor / outdoor PM levels and EC surrogate, at typical microenvironments in the Athens area

The aim of the present work was to characterize particulate matter (PM) and elemental
carbon (EC) indoor and outdoor concentration levels in the Athens area and to examine the
contribution of ambient air to the observed indoor levels.
24-hr simultaneous indoor and outdoor PM10 and PM2.5 measurements were conducted at a
central (CR) and a suburban (SR) residence, and at an office in the commercial centre of
Athens (CO), during cold and warm period of 2006. The absorption coefficient (α) was
measured on the collected filters, as a surrogate for EC concentration levels.
Ambient PM levels were very high at both central sites and significant at SR (mean 24-hr
PM10: 87.4, 50.3 and 87.3 μg m-3 and PM2.5: 50.7, 20.2 and 42.8 μg m-3 at CR, SR and CO).
The measured absorption coefficient values were very high at CR and CO for both size
fractions.
Indoor PM concentration and absorption coefficient values were lower than the respective
outdoor ones, but still significant at the two central sites.
Very good correlations were observed between indoor and outdoor data (especially for
absorption coefficient values), indicating a large contribution of the ambient atmosphere to the
indoor levels, more pronounced in finer particles.