Analysis of the Correlation between Particulate Matter Concentrations and Traffic Volume in the Metropolitan City of Ulsan, Korea

Road vehicles, such as cars, trucks and buses, can produce significant amount of particular matter (PM) in urban areas. This study analyzes the correlation between air concentrations of PM (PM2.5, PM10, TSP (total suspended particulate)) and traffic volume near road sides in the metropolitan city of Ulsan, Korea. 9 road sides or areas selected for the study included a traffic rotary, 2 circulation roads (an industrial road and a car road), 4 downtown roads (including city hall) in Nam-gu, 1 residential area road in Chung-gu, 1 residential and industrial road in Dong-gu, which might represent major traffic density in Ulsan. A beta-ray attenuator and a high volume air sampler were used for sampling of PM during 3 classified time periods (morning, afternoon, evening) in a sampling day. Traffic volume has been counted using a manual counter during each PM sampling. High correlations were identified between PM concentrations and traffic volume [PM2.5 vs (heavy duty vehicles (HDV) + small vehicles (SV)), PM2.5 vs SV, PM10 vs (HDV+SV), PM10 vs SV, and TSP vs (HDV+SV)]. Also, significantly high correlations were obtained between PM concentrations [PM2.5 vs PM10, PM10 vs TSP, PM2.5 vs TSP, afternoon PM2.5 vs evening PM2.5, and afternoon PM10 vs evening PM2.5]. However, the correlations between PM10 and HDV and between TSP and HDV were very weak. PM concentration characteristics obtained from the circulation road that its traffic mostly consists of small cars and its environment has a lot of green areas were quite different from those obtained from the road sides passing downtown or residential areas of Ulsan.