This project investigates the characteristics of PM2.5 and the sources of its emissions in Taichung City. This study includes a component analysis of ambient PM2.5, stack emission monitoring of PM2.5, measurement of visibility, and an investigation on the air quality impacts by the largest PM2.5 industrial emitters.
The health impacts of PM1 are more detrimental than that of PM2.5. We find that PM2.5 in Taichung is primarily composed of particulate matter smaller than 1μm, with PM1 accounting for about 80% of PM2.5. In terms of the constituents of PM2.5, elemental carbon and organic carbon have more severe health impacts than sulfates and nitrates. Elemental carbon and organic carbon together account for 47.1% of PM2.5, whereas they account for 51.7% of PM1 in the Dali area. From the perspective of public health, the regulation of emissions from gasoline-powered vehicles in Dali should be a priority. Control measures should aim to reduce the number of vehicles, increase the use of electric vehicles, and tighten regulatory emission standards for gasoline-powered vehicles.
Investigation of PM2.5 from discharge pipes of three electric arc furnaces in the City shows that FPM was between 0.29 mg/Nm3～1.23 mg/Nm3, CPM was between 0.09 mg/Nm3～2.00 mg/Nm3, and PM2.5/TSP was in the range of 0.12～1.23. Iron (Fe) and zinc (Zn) were the most abundant components in FPM, the reason being that galvanized steel (zinc-coated steel) accounted for the most substantial proportion of scrap steel.
Using HYSPLIT with data from 2016, we generated five scenarios under the influence of the sea breeze. The trajectory analysis indicates the emissions from the Taichung Power Plant might travel via three paths:
1.Traveling across the Dadu Plateau and entering the Taichung City;
2.Entering the eastern mountain area, via the Dadu Plateau and the Bagua Valley; and
3.Traveling along the eastern side of the Bagua Mountain towards the southeast.
Emissions have the most considerable impact on the air quality of Taichung City when they travel via the first path. Selecting 2016 as the year of simulation is based on the calculation of the latest TEDS10 emissions using 2016 as the base year. Simulation results of the five scenarios in 2016 from CMAQ indicate that the maximum hourly contributions of PM2.5 by the Taichung Power Plant and the Dragon Steel Corporation are the highest in Shalu, among all Taichung City locations, reaching as high as 21.7μg/m3 and 9.0μg/m3. In these case, high-pollution days are chosen as the examples, which are not covered all air quality status. The Taichung Power Plant has reduced coal by 24% now, at the same time, the contribution of PM2.5 will also be reduced.
We used forecasted AQI values by the Environmental Protection Administration. With the aid of machine learning and a neural network-like method for optimization, we calculated the accuracy of forecasted AQI>100 to be over 83% for all individual locations in Taichung. Overall, for AQI= 101～150, the average accuracy was 88%, and for AQI>150, the average accuracy was 92%.
