In 2015, air pollutant emissions in the Republic of Korea were 792,776 metric tons of CO, 1,157,728 metric tons of NOx, 352,292 metric tons of SOx, 604,243 metric tons of TSP, 233,177 metric tons of PM10, 98,806 tons of PM2.5, 15,934 metric tons of BC, 1,010,771 metric tons of VOCs, and 297,167 metric tons of NH3. Among major emission source categories, the main emission sources and the contributions to emissions, by pollutant, were as follows: road transport (31.0%), biomass burning (29.3%), and non-road transport (17.1%) for CO; road transport (31.9%), non-road transport (26.3%), and manufacturing industry (14.6%) for NOx; industrial processes (29.9%), energy production (25.9%), and manufacturing industry (24.2%) for SOx; fugitive dust (67.6%) manufacturing industry (20.1%) for TSP; fugitive dust (47.0%) and manufacturing industry (30.4%) for PM10; manufacturing industry (36.8%), fugitive dust (17.5%), and non-road transport (14.3%) for PM2.5; road transport (42.0%) and non-road transport(39.6%) for BC; solvent use (54.9%) and industrial processes (18.1%) for VOCs; and agriculture (77.8%) and industrial processes (13.3%) for NH3. The data we calculate can be used as official national emissions data for the establishment, implementation, and assessment of air quality-related policy, such as measures to deal with particulate matter, as well as for related modeling and other research.

In 2016, air pollutant emissions in the Republic of Korea were 795,044 metric tons (hereafter tons) of CO, 1,248,309 tons of NOx, 358,951 tons of SOx, 611,539 tons of TSP, 233,085 tons of PM10, 100,247 tons of PM2.5, 16,401 tons of BC, 1,024,029 tons of VOCs, and 301,301 tons of NH3. Including energy production, thirteen emission sources, which comprise the national air pollutant emission inventory, were classified by their characteristics into five sectors (Energy, Industry, Road, Non-road, and Everyday Activities and Other Emission Sources) to analyze their relative contributions to the national emissions. Specifically, their contributions by pollutant were as follows: NOx (11.0%), SOx (21.9%), PM2.5 (3.2%), VOCs (0.8%), NH3 (0.5%) from the energy sector; NOx (20.2%), SOx (59.7%), PM2.5 (42.1%), VOCs (24.3%), and NH3 (14.4%) from the industry sector; NOx (36.3%), SOx (0.1%), PM2.5 (9.7%), VOCs (4.6%), and NH3 (1.7%) from the road sector; NOx (24.8%), SOx (11.5%), PM2.5 (14.3%), VOCs (4.0%), and NH3 (0.04%) from the non-road sector; and NOx (7.6%), SOx (6.7%), PM2.5 (30.6%), VOCs (66.3%), and NH3 (83.4%) from the everyday activities and other emission sources sector. The data we calculate are used as official national emissions data for the establishment, implementation, and assessment of national atmospheric environment policy to improve air quality. As critical and necessary materials, the data are also utilized on a wide range of studies on policies such as customized regional particulate matter reduction measures. Thus, it is crucial to estimate highly reliable national emissions by enhancing the emissions factors and inventory and to establish a scientific emissions testing system by using air quality modeling and satellite data.

Various shipping emissions controls have recently been implemented at both local and national scales. However, it is difficult to track the effect of these on PM2.5 levels, owing to the non-linear relationship that exists between changes in precursor emissions and PM components. Positive Matrix Factorisation (PMF) identifies that a switch to cleaner fuels since January 2020 results in considerable reductions in shipping-source-related PM2.5, especially sulphate aerosols and metals (V and Ni), not only at a port site but also at an urban background site. CMAQ sensitivity analysis reveals that the reduction of secondary inorganic aerosols (SIA) further extends to inland areas downwind from ports. In addition, mitigation of secondary organic aerosols (SOA) in coastal urban areas can be anticipated either from the results of receptor modelling or from CMAQ simulations. The results in this study show the possibility of obtaining human health benefits in coastal cities through shipping emission controls.

According to the 2018 National Air Pollutant Emissions Inventory (NEI), air pollutant emissions in the Republic of Korea comprised 808,801 tons of CO, 1,153,265 tons of NOX, 300,979 tons of SOX, 617,481 tons of TSP, 232,993 tons of PM10, 98,388 tons of PM2.5, 15,562 tons of black carbon (BC), 1,035,636 tons of VOCs, and 315,975 tons of NH3. As for national emission contributions to primary PM2.5 and PM precursors (NOX, SOX, VOCs, and NH3), major source categories were the road sector for NOX, the industry sector for SOX and PM2.5, and the everyday activities and others sector for VOCs and NH3. In the case of emissions by region, the largest amount of NOX was emitted from the Seoul Metropolitan Areas (SMA; Seoul, Incheon, and Gyeonggi-do, hereafter SMA) and the largest amounts of SOX, PM2.5, VOCs, and NH3 were from the Yeongnam region. A 3D chemical transport modeling system was used to examine the uncertainty of the national air pollutant emissions based on the National Emission and Air Quality Assessment System (NEAS). Air quality was simulated using CAPSS 2018, and the simulation data were compared with observed concentrations to examine the uncertainties of the current emissions. These data show that emissions from five si (cities) (Pohang, Yeosu, Gwangyang, Dangjin, and Ulsan) need to be improved. Most of all, it is necessary to examine the emissions from places of business that use anthracite, which is the major PM2.5 emission source, as fuel in these areas.

When a vehicle travels an unpaved road, the force of the wheels on the road surface causes pulverization of surface material. Particles are lifted and dropped from the rolling wheels, and the road surface is exposed to strong air currents in turbulent shear with the surface. The turbulent wake behind the vehicle continues to act on the road surface after the vehicle has passed.The particulate emission factors presented in the previous draft version of this section of AP-42, dated October 2001, implicitly included the emissions from vehicles in the form of exhaust, brake wear, and tire wear as well as resuspended road surface material 25 . EPA included these sources in the emission factor equation for unpaved public roads (equation 1b in this section) since the field testing data used to develop the equation included both the direct emissions from vehicles and emissions from resuspension of road dust.