Visualizing changes in nationally averaged PM_(2.5) concentrations by an alluvial diagram

摘要

Ailments related to ambient fine particulate matter (PM2.5) cause 3.22 million deaths per year on average worldwide, which, along with high blood pressure and tobacco smoking, is defined as the leading risk factor for global burden of disease (Lim et al, 2013). The alluvial diagram displayed in Figure 1 demonstrates the temporal changes in the ranks of nationally averaged PM2.5 concentrations of developed areas from 1998 to 2013 (Rosvall and Bergstrom, 2010). A 'developed area' within a country was delineated using the Defense Meteorological Satellite Program's Operational Linescan System annual stable lights image composites with pixels' digital number values equal to or larger than 10 (Zhao and Samson, 2012). A total of 46 countries with at least 10 identified developed areas in the 1998 stable lights image product are included in the alluvial diagram (Doll et al, 2000). Here each wide line in the alluvial diagram is called an alluvium. PM_(2.5) concentrations were extracted from a satellite-derived gridded PM_(2.5) datasets (van Donkelaar et al., 2016). This dataset is considered to be one of the most accurate global PM_(2.5) concentration image products at the 0.01° × 0.01° (or 1 km × 1 km) spatial resolution and has been used in applied public health studies (van Donkelaar et al., 2015).