Analysis of NO2 gas concentration from the transportation sector through direct measurement and the Caline 4 dispersion program on the Makassar City Toll Road

Makassar as a developing city is experiencing development from the transportation sector. This resulted in the increasing number of vehicles. The increase in the number of vehicles produces emissions that cause air pollution, including NO2 emissions from motor vehicles. Currently NO2 concentration can be determined by direct measurement using the Gries Saltman method and pollutant prediction using the Caline program. This research was conducted on the Makassar city toll road which is divided into nine sample points. This study aims to determine the level of NO2 concentration from the transportation sector on the Makassar city toll road. Concentration results from direct measurements and predictions of caline are compared to show the level of concentration present. The results of the NO2 concentration are still below the threshold value that has been set in the latest applicable regulations, which is 200 g/Nm3 with a measurement time of 1 hour. The high or low value of NO2 concentration is influenced by the vehicle volume factor, where the NO2 concentration increases along with the increase in vehicle volume. In addition, it is also influenced by meteorological factors. Based on the results of the Caline-4 software output, the results obtained from the distribution of NO2 concentrations at each receptor found on the Toll Road in Makassar City, it can be stated that it is still below the threshold value set in the latest applicable regulations, which is 200 g/Nm3 with time measurement for one hour.