Improper disposal of cigarette butts in a southeast Asian megacity (Hanoi, Vietnam): Pollution indexes, distribution profiles, and preliminary physicochemical characterization.

ABSTRACT

Although Southeast Asia is among the largest producers and consumers of cigarettes in the world, information about environmental contamination with littered cigarette butts (CBs) in this region is very limited, especially in urban areas. In this study, we collected CBs in 58 locations of 6 categories (i.e., parks, apartments, streets, shopping malls, universities, and relic sites) in Hanoi, a megacity of Vietnam, to elucidate the occurrence, pollution levels, and physicochemical properties of this specific waste type. A total of 25,943 CBs with 86 brands from 16 origin countries was obtained, showing a density range of 0.0056 to 1.16 (mean 0.125) CB/m2 and cigarette butt pollution index (CBPI) range of 0.23 to 86.9 (mean 6.14). CB contamination levels were higher in parks, apartments, streets, and shopping malls than in universities and relic sites, but CB density and CBPI values varied greatly between locations of the same category. Generally, CB contamination levels measured in Hanoi were within a moderate range compared to other countries worldwide. Several physicochemical properties of CBs were preliminarily determined, which partly confirmed the formation of smoking-derived chemicals captured in CBs and their release potentials into surrounding environments. Further investigations are required to evaluate detailed chemical profiles, leaching behavior, and toxic effects of hazardous substances in CBs.