Abstract
Keywords:
Roadside measurement, Particle size distribution, Vehicle exhaust, Ultrafine particles
Abstract
The atmospheric environment was highly affected by vehicle emission in metropolitan area. Particularly, the ambient air on roadside might depend directly on the traffic. In this study, measurements of particle number size distribution in the 16-625-nm range have been made on the side of the busy Sungsan Road in central Seoul from 18 to 23 March 2005. The CO and NOx concentrations were also continuously monitored. The diurnal and weekly variations were analyzed. The particle number concentration tends to peak in the early morning and later evening which has most traffic flows. In real circumstance of roadside within complex dilution conditions, main exhausted-particle sizes were below 100nm, especially in the 30-60-nm range. At the midday times having most sunlight, particles in the 16-30-nm range behave anomalously showing peak concentration. Particles in this fraction tend to be formed nucleated particles as result of photochemical reaction. The correlations between particle and gas concentrations were confirmed obviously. The particle number concentration highly correlated (R>0.75) with NOx through a wide range of particle sizes.