Reduction Efficiency of Secondary Organic Aerosols by Emission Reduction Scenarios of Volatile Organic Compounds in Ulsan

Abstract

Volatile Organic Compounds (VOCs) are a major precursor generating ozone (O3) and Secondary Organic Aerosols (SOAs) by reacting with nitrogen oxides (NOX) and OH radicals in the atmosphere. In this study, the scenarios of VOC emission reduction in Ulsan were suggested based on two emission inventories: the Clean Air Policy Support System (CAPSS) and the Pollutant Release and Transfer Register (PRTR). Considering the characteristics of VOC emissions, three scenarios of VOC emission reduction were derived: (1) Scenario 1-1 reducing TVOC emissions by the type of emission sources, (2) Scenario 2-1 reducing BTEX emissions by areas and compounds, and (3) Scenario 3-1 reducing BTEX emissions by the type of industrial facilities. The concentrations of VOCs before and after the emission reduction were simulated using an air dispersion model. Then, their corresponding Secondary Organic Aerosol Formation Potential (SOAFP) was calculated, and reduction efficiencies in VOCs and SOAFP were compared among the three scenarios. Scenario 2-1 showed the most significant decrease in VOC concentrations. Scenarios 1-1 and 2-1 presented higher reduction efficiencies of VOCs and SOAFP than control scenarios that reduce the same emission amounts without considering emission characteristics (i.e., industrial facilities, areas, and compounds). The methodology and major results of this study can be a basis for establishing VOC and SOA management policies.