Based on the need of air quality modeling regulation and upgrade of Gaussian diffusion model application in Taiwan, the AERMOD system suitable for Taiwan was established and the preparations for AERMOD to be announced as regulation model was also completed in the study. The updates and announcements of relevant information for air quality modeling increments, information are published on the AQMC website. The revisions for the regulations of "Air Quality Model Simulation Specification" and "Tolerable Incremental Limits of Air Pollutants" have been completed after a series of procedures in the study. The draft version of revision for the regulations of "Technical Specifications for Air Quality Model Assessment", "Principle of Offset Treatment of Air Pollutant Emissions in Development Behavior", and "Simulation Specification for Air Quality Policy Assessment" have been proposed in the study. Technical examinations of air quality modeling for Stationary Pollution Source Installation and Operating Permit and technical review and analysis of air quality modeling for the application cases of environment impact assessment were also implemented to assist EPA in the study.
In response to the research and evaluation of fine Particulate Matter (PM2.5) and ozone (O3) pollution improvement strategies, the dynamic changes for the long-range transport of overseas influence on Taiwan. The PM2.5 and O3-related air quality simulation and performance evaluation for January, April, July, and October 2019 have been done in this study. The influences of cross county/city/air basin transport and three kind of anthropogenic sources including point (industry), line (vehicle), and area (fugitive) emissions on atmospheric PM2.5 and DM8O3 (daily maximum 8-hour average O3) in Taiwan have also been simulated and studied. In the study of cross air basin transport effect on PM2.5, the emission of North, Chu-Miao and Central air basin performed significant effect, 21%-34%, on PM2.5 concentration of southern part of Central air basin. In the study of three kind of anthropogenic sources effect, the annual average concentrations of PM2.5 at all air basin in Taiwan were most affected by the area source, followed by the line source. The results show that the higher PM2.5 pollution level, the higher PM2.5 ratio contributed by Taiwan-self emission, and the anthropogenic sources of Taiwan can contribute as high as up to 65% under the very unhealthy level of PM2.5 pollution (PM2.5 ≥ 70.5 μg/m3). In the study of cross air basin transport effect on DM8O3, the emission of North air basin performed the highest effect (11.8%) on Taiwan's DM8O3, while the emission of Central air basin was second (5.8%). The highest effect on Taiwan's DM8O3 was line source (12.2%), followed by point source (8.1%); while the higher DM8O3 pollution level, the higher DM8O3 ratio contributed by Taiwan-self emission, and the contribution can be as high as up to 51% under the unhealthy level of DM8O3 pollution. The simulation results also showed that the NMHC emission reduction can improve the O3 concentration for whole area in Taiwan. However, the NOx emission reduction only (without NMHC reduction) may result O3 increase in some area in Taiwan. Therefore, it is recommended that the reduction ratio of NMHC emission should be larger than the one of NOx emission. The simulation results of long-range transport showed that the annual average concentration of DM8O3 in Taiwan in 2019 is about 34% contributed by Taiwan-self emission, 29% transported by East Asia emissions, and 38% affected by the background of East Asia; while the annual average concentration of PM2.5 in Taiwan is about 53% contributed by Taiwan-self emission, 44% transported by East Asia emissions (including East Asian countries and international shipping), and 3% affected by background of East Asia. Due to the importance of long-range transport from, the emission reduction of East Asia emission will be good for the improvement of ozone and PM2.5 in Taiwan, besides Taiwan's own efforts.