## 5 Discussion  
According to the results, the air quality of Kaohsiung needs to be improved by identifying key pollutants, then making effective strategies. In summary, the gap value of mobile air pollution sources (\(D_{2}\)) is the largest, with Scooters (\(C_{22}\)) and Diesel vehicles (\(C_{21}\)) listed in the first and second places. There are many scooters and diesel vehicles in the city, leading to a high degree of historical reliance on such transportation tools. Encouraging electronic vehicles might be a necessary method to achieve the replacement effect. This requires the local government to invest more in subsidy for electronic vehicles for individual and industrial transportation uses.  
Because there are coal-fired power plants supporting heavy industries' growth, which is a major strategy of Kaohsiung's economic development., the criteria gap value of coal-fired power plants (\(C_{11}\)) and factories (\(C_{12}\)) are the first and second largest. According to statistics [11], almost 50% of all monitored (highly pollutant) factories of Taiwan are in Kaohsiung. Moreover, the largest refinery, petrochemical industrial zone and steel plant of Taiwan are also in Kaohsiung. For a long time, policy makers often neglected the upgrading of energy-consuming industries and pollutant processing industries by sacrificing the ecological environment in exchange for economic development. However, scholars have found that energy-consuming industries can cause carbon emissions and pollute the environment, but they do not necessarily lead to economic growth [65; 66]. Therefore, in the long run, policymakers should consider implementing more aggressive policies to support energy-consuming industries and power plants to improve their efficiency without affecting economic growth [67].  
The improvement strategy of this study could be discussed in dimensions and criteria. In terms of dimensions, through the facet of INRM, it can be seen that mobile air pollution sources (\(D_{2}\)) are affected by stationary air pollution sources (\(D_{1}\)). Therefore, policymakers need to consider the impact of stationary air pollution sources on mobile air pollution sources. In terms of stationary air pollution sources, experts hope to improve coal-fired power plants (\(C_{11}\)), but it is affected by certain factors (\(C_{12}\)). In other words, when thinking about how to improve air quality, policy makers should not just prioritize resources to reduce the level of power plants, but they should help the factory to install  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Dimensions/Criteria** & **Local Weights** & **Global Weights** & **Performance** & **Gap** \\ \hline
**Stationary air pollution sources (\(D_{1}\))** & **0.44** & & **2.27** & **0.43** \\ \hline Coal-fired power plants (\(C_{11}\)) & 0.14 & 0.06 & 1.00 & 0.75 \\ Factories (\(C_{12}\)) & 0.16 & 0.07 & 1.20 & 0.70 \\ Agriculture-related emissions (\(C_{13}\)) & 0.13 & 0.06 & 2.30 & 0.43 \\ Construction dust (\(C_{14}\)) & 0.14 & 0.06 & 2.90 & 0.28 \\ Cooking fumes (\(C_{15}\)) & 0.14 & 0.06 & 3.30 & 0.18 \\ Custons (\(C_{16}\)) & 0.16 & 0.07 & 3.00 & 0.25 \\ River dust (\(C_{17}\)) & 0.15 & 0.07 & 2.30 & 0.43 \\ \hline
**Mobile air pollution sources (\(D_{2}\))** & **0.56** & & **1.61** & **0.60** \\ \hline Diesel vehicles (\(C_{21}\)) & 0.22 & 0.12 & 1.10 & 0.73 \\ Scooters (\(C_{22}\)) & 0.33 & 0.18 & 1.00 & 0.75 \\ Ship emissions (\(C_{23}\)) & 0.26 & 0.15 & 2.30 & 0.43 \\ Railway transportation (\(C_{24}\)) & 0.19 & 0.11 & 2.30 & 0.43 \\ \hline Total performance & & & 1.90 & \\ Total gap & & & & 0.52 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Performance evaluation of the empirical case using modified Vlse Kriterijuska Optimizacija Komonornsno Resenje (VIKOR).  
anti-fouling equipment through counselling mechanisms, requiring plants to gradually improve the power saving efficiency of the machine, reducing the burden on the power plant, increasing the monitoring equipment, and strengthening the elimination of excessive factory emissions.