Successful air quality management program in central Taiwan?

This paper reviews the changes of the spatial-and-temporal distributions of air pollutants over central Taiwan after 1995, when stationary sources and automobiles were taxed for their airborne-pollutant emissions by Taiwan EPA. Since then, many control strategies have been implemented for improving regional air quality. SO₂ emission from point sources has been reduced by 50% from 1997 to 2000. Emissions from Highway #1 in 2001 were less than 1997 by 10-64%. As a result, the concentrations of primary pollutants (SO₂, CO, NO_x and NMHC) along the highway and the two power plants have reduced. Contour as well as air quality modeling analyses are performed to quantify the source/receptor relationships of primary and secondary pollutants such as SO₂, NO_x, CO, NMHC, PM₁₀ and O₃. These analyses prove that the emission reductions from the highway and the power plants cause:1) the concentration reductions of the primary pollutants along the highway and locations near the power plants and 2) possible ozone concentration reduction at 80 km leeward from Tunghsiao Power Plant. Nonetheless, O₃ concentration over the entire region is still in a rise in general, which is most likely ironically connected to NO emission reduction from automobiles. This automobile-NO-emission reduction inhibits surface O₃ to be titrated by NO. The emission inventory and the concentration datasets of the air-quality management history offer a unique opportunity for understanding how well and how bad the current state-of-art air quality models are. It shows the largest discrepancy between modeled and observed concentration change is the impact of high stack NO emission on surface O₃ concentration.