Spatial and temporal variation of CBPI and leakage of heavy metals from cigarette butts into the urban environment.

More than 5 trillion cigarettes are produced in the world every year. This hazardous waste is one of the most important litter in the environment. The purpose of this study was to investigate the density and dispersion of cigarette butts in the urban environment and to estimate the leakage of pollution from it to the environment. For this purpose, the cigarette butt pollution index was used in 14 locations. Observations were made during a year and once a month for each location. The study of the locations was done with the same conditions on weekend and working days. The amount of heavy metal leakage was estimated based on the average weight of cigarette butts and the ratio of metal leakage in different weather conditions. The results showed that the annual average of index for the studied locations was 1.36 (SD 0.11) to 10.6 (SD 1.23). Based on this, 28.5% of the locations were in the low pollution status and 42.8% were in the significant pollution status and worse. On average, the index on weekend decreased by 32.3 percent in all locations, and the average index of the studied locations in spring and summer was 26.2 percent higher than in autumn and winter. The average leakage of heavy metals including chromium, cadmium, zinc, lead, copper, and nickel from littered cigarette butts in commercial, residential, and recreational areas was estimated to be 0.27, 0.079, and 0.17 µg per square meter, respectively. Cigarette butt is one of the most abundant litter in the studied area, which is the source of many pollutants, including heavy metals. This hazardous waste is a serious threat to the urban environment.