The primary goal of air quality policies is to reduce the impact of air pollution on human health, in particular, it is very important in the attainment-closing geographic areas with densely populated like Taiwan. Air quality policies in general only consider the reduction of emission as well as concentration, in order to highlight the effects of air pollution reduction responded on human health, a health index using PM2.5 concentration reductions (HI-cr) was adopted to evaluate air quality policies in this study. To investigate priorities of cross-administrative region air quality policies, the HI-cr were calculated by using annual results of atmospheric modeling and air quality modeling, which involved the meteorological effect and spatial distribution of air pollution. By studying the emission reduction targets of three administrative regions, Taichung, Changhwa, and Nantau in the Central Taiwan, 8 reduction scenarios were designed and examined. It is found that HI-cr can present detailed information in human health.From the results of adaptability assessement based on health, the equal reduction of emission in present air quality policy gave the most concentration reduction area with lower HI-cr. But according to the analysis in different proportion of emission reduction scenarios, it found that emission reduced more in the most population region, even the concentration reduction is not the highest but HI-cr increased. According to the analysis of different emission reduction policies, this study suggests HI-cr is an important index to evaluate the air pollution control policies instead of considering the impact of air pollutant concentrations only, especially in cross-administrative regions.Implications: In this study, we present a modified health index, HI-cr, to determine the priority of cross-administrative air quality policies using PM2.5 concentration reduction. HI-cr is adaptable for any types of geography, in particular for areas where the air quality is almost attainment like Taiwan. Cross-administrative air quality policies could be evaluated using HI-cr, it could highlight the high performance on population health improvement rather than high concentration reduction. In particular, for economies where the air quality is almost attainment and with complex terrain and dense population, air quality policies should consider the health prevention issues.