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The present study utilizes air quality modeling to probe the sources and characteristics of PM 2.5 (particles less than 2.5 micrometers in aerodynamic diameter) at the northern tip of Taiwan (CAFE station) in the early stage of the Asian haze period. Since CAFE is the first place that is influenced by the Asian haze coming from the north, this study focused on the wind field, PM 2.5 concentration, and PM 2.5 composition at CAFE. During the research period (Oct. 16, 2015, to Nov. 15, 2015, four PM 2.5 episodes occurred at CAFE. This study classified these four episodes into three types, according to their PM 2.5 sources: the long-range transport (LRT) type, the local pollution (LP) type, and the LRT/LP mix type. For the LRT type, Asian outflows prevailed in a north to northeast wind at the north of Taiwan. The proportion of NO 3 -in the PM 2.5 resolvable compositions was very small at CAFE due to evaporation during transport, whereas the relative proportion of sea salt increased due to strong winds. For the LP type, an east wind prevailed and formed a cyclone/lee vortex in northwest Taiwan. Although the background PM 2.5 concentrations were low (4-20 µg m -3 ), the cyclone transported local anthropogenic emissions northward and elevated the PM 2.5 levels at CAFE. For the LRT/LP mix type, an east wind also prevailed, but the background PM 2.5 concentrations were at an intermediate level (20-30 µg m -3 ) because the Asian outflows had already transported haze to the West Pacific. The combined LRT and LP increased PM 2.5 at CAFE. In addition, the proportions of NO 3 -(nitrate) for the LP and LRT/LP episodes were obviously higher than those on the days before and after. This suggests a considerable contribution on PM 2.5 from LP.

The Asian region is one of the major emission sources of air pollution. Although ambient PM2.5 has been linked to several health risks in high-, low-, and middle-income countries, the further analysis of type impact is still rare but significant. The PM2.5 distribution retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer) aerosol optical depth products within 16 years thus explored the associations between under-five and maternal mortality for 45 countries in Asia. Both the nonparametric (Generalized Additive Mixed-Effect) and parametric (Generalized Linear Mixed-Effect) models were employed to analyze the collected datasets. The results show that the levels of PM2.5 in Asian sub-regions were higher than the Global Air Quality Standards. Biomass PM2.5 concentrations was associated with increased the rate of under-five (Incidence Rate Ratio, IRR = 1.29, 95% CI, 1.13–1.47) and maternal (IRR = 1.09, 95% CI: 1.08–1.10) deaths in Asia. Anthropogenic PM2.5 was associated with increased rate of under-five deaths in Asia by 12%. The nonparametric method revealed that dust PM2.5 was positively associated with the under-five (β = 0.04, p < 0.001) and maternal (β = 0.07, p < 0.001) deaths in Asia. The rate of maternal deaths was increased by biomass/dust (IRR = 1.64, 95% CI: 1.63–1.65) and anthropogenic/dust (IRR = 1.22, 95% CI: 1.19–1.26) mixture types. In summary, long-term exposure to different types of ambient PM2.5 in high concentration increased the rate of under-five and maternal deaths, suggesting that policies focusing on preventive and control measures is imperative for developing an improved maternal, newborn, and child health in Asia.

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