Relationships between particle number and mass concentrations in an urban area

Abstract

The PM10, PM2.5, and PM2.5-10 mass concentrations along with fine particle absorbance (PM2.5, abs) and particle number (PN) in the metropolitan area of Athens, Greece were studied. The sampling site was an urban background site in the city center, 50 m from the nearest road with traffic density of ≈ 10,000 vehicles/day. The measured PM2.5 and PM10 concentrations were comparable and higher than those measured in urban areas in Western Europe and US, providing additional evidence of the north-to-south and west-to-east concentration gradient. Particle number concentration measurements were similar to those measured in major urban and industrial areas in Western Europe. Higher particle number concentrations were measured during winter compared to those during summer. This pattern was caused by both variations of particle sources in time and prevailing meteorological conditions. In particular, increased traffic emissions along with emissions from diesel-powered boilers used for domestic heating resulted in higher particle number concentrations during wintertime. While no seasonal pattern was observed for fine and coarse particle mass, wintertime particle number concentrations were substantially higher than those measured during the summer due to differences in particle number sources and local air circulation. This is an abstract of a paper presented at the AWMA Associations 99th Annual Conference and Exhibition 2006 (New Orleans, LA 6/20-23/2006).