Quantify the pollution from discarded cigarette filters.
An estimated 4.5 trillion cigarette butts are discarded annually worldwide, making them the single most common form of litter. Each filter is made of cellulose acetate, a plastic that takes 10-15 years to decompose and never fully biodegrades — it breaks into microplastics. A single cigarette butt can contaminate up to 40 liters of water with nicotine, heavy metals (cadmium, lead, arsenic), and polycyclic aromatic hydrocarbons. Studies show one butt per liter of water is lethal to marine and freshwater fish within 96 hours. The tobacco industry has resisted Extended Producer Responsibility (EPR) laws, but countries like France and Spain now require manufacturers to fund cleanup. Filter-free cigarettes or biodegradable filters could reduce this pollution, but adoption remains minimal.