Ultrafine particle and gas contamination of urban air in Seoul, Korea, during winter

Abstract

To investigate the contamination characteristics of ultrafine particles and gases originating from vehicle exhaust, data were obtained from one-week intensive monitoring at an urban site in Seoul, Korea during the winter of 2003. The diurnal variations of size-segregated particle concentrations for both ultrafine particles (20-100 nm) and accumulation mode particles (100-600 nm) were very similar. Strong morning peaks and weaker evening peaks of ultrafine particles and NOx were observed at the site. The NOx concentration closely followed the trend of ultrafine particle concentration, resulting in a high determination coefficient (R-2 = 0.65) for the relationship between these two pollutants. When the wind conditions were favourable for the transport of the air pollutants from busy neighbouring roads to the monitoring site, the frequency of simultaneous observations was increased. Both ultrafine particles and NOx were determined to be good indicators of the transport of vehicle emissions from roads to urban surroundings.