Abstract
Motor vehicles are known as a main source for particulate matters, especially ultrafine particles (<100 nm). Several epidemiological studies have shown a relationship between high number concentration of ultrafine particles and adverse health effects. An air quality management in the localized area is complex and needs an exhaustive study. It is difficult to characterize vehicular air pollution at the roadside because of much variation in meteorological conditions and short information about vehicle fleet. Tunnel measurement, however, can reduce those disadvantages. Exhaust gas emitted from motor vehicles inside a roadway tunnel is thought to be much more harmful than the ambient air due to high vehicle density but limited air movement as well as meteorological affected. There is no data available on particle number concentration in a roadway tunnel in Korea. The purpose of this study, therefore, is to characterize the vehicular air pollution in roadway tunnel and to supply measurement data for calculation of emission factors of ultrafine particles based on particle number in the roadway tunnel. Tracers of vehicle emission such as ultrafine particles, NOx, CO, and black carbon were monitored at two locations of a roadway tunnel for 3 days. Diurnal variations and relations among the indicators of vehicle exhaust were investigated. The ultrafine (20 – 100 nm) particle concentration (UPC) of location B, which is further from the tunnel entrance than location A, was significantly higher than that of location A, which is 10 times higher than that at the main roadside in Seoul. The concentrations of gas pollutants were also severally contaminated and well correlated with UPC in this study.
Keywords: Ultrafine particle, PM10, vehicle exhaust, tunnel measurement, particle number concentration