STUDY OF IN-VEHICLE PARTICULATE MATTER EXPOSURE IN THESSALONIKI, GREECE

The proximity of vehicles to emissions from other vehicles on freeways and busy roadways leads to elevated pollutant concentrations in vehicle cabins compared to other indoor environments. This study presents in-cabin and outdoor measurements of particulate matter concentration and size distributions while driving on busy streets of the centre of Thessaloniki, Greece. Measurements were carried out during 4 consecutive days (07:00 - 15:30) of July and were performed using an optical counter (TSI Optical Particle Sizer Model 3330). Three different in-cabin ventilation settings were evaluated: a) open windows, a ventilation mode that brings in outside air, b) air condition (AC) on and c) AC and recirculate (RC) on. Overall car protection as well as commuter exposure were estimated based on in-cabin and outdoor concentrations. Outdoor measurements during the days of experiment varied with median values for PM10 at 31 ug/m3 (range: 13 - 131 ug/m(3)) and for PM2.5 at 5 ug/m(3) (range: 3 - 19 ug/m3). "Open windows" is the ventilation mode at which the highest concentration levels were observed (PM10 median, min, max: 34, 11, 160 ug/m3 and PM2.5 median, min, max: 6, 3, 21 ug/m(3)). The air-recycling mode leads to a clear reduction in the concentration inside a vehicle. Specifically, shifting from "open windows" to "AC and RC on" mode, leads to an average reduction by 72% for PM10 and by 50% for PM2.5. The average reduction while changing from "open windows" to "AC on" was 64% for PM10 and 46% for PM2.5. The ratio between PM10(out)/PM10(cabin) and PM2.5(out)/PM2.5(cabin) was 0.78 (s.d. 0.07) and 0.81(s.d. 0.15) respectively. This study contributes to a better understanding of human exposure to particulate matter and provides information regarding the accumulation of particles in private vehicles. It is clear that the ventilation settings have a major effect on the levels of exposure.