AN ANALYSIS OF PM2.5 USING THE DIRECTED ACYCLIC GRAPH: A CASE STUDY OF SOUTHEAST ASIA

In this study, we used the directed acyclic graph (DAG) to analyze a dataset of PM2.5 concentrationlevels in 11 cities in Southeastern Asian countries for the period of March 18 to April 11, 2021. Thisis the period that PM2.5 posted a major problem for several cities in Southeast Asia. We analyzedthe data to determine the effect of the PM2.5 concentration in each city on that of each of the othercities. The results show that the PM2.5 concentration in Yangon, Myanmar, had a direct effect onthe PM2.5 concentration in Chiang Mai, Thailand, and that the PM2.5 concentration in KualaLumpur, Malaysia, had a direct effect on the PM2.5 concentration in Singapore, Republic ofSingapore. Where one country has a direct effect on another, a reduction or increase of PM2.5 in theformer will reduce or increase, respectively, the PM2.5 concentration in those on which it has aneffect. Given this relationship, if the concentration of PM2.5 is to be reduced either overall or in anyspecific country is to be reduced, international cooperation will be essential. Our application ofDAG to this environmental issue exemplifies the viability of this technique for exploring andindicating solutions for real-world problems more generally.