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Chemical emission rates per cigarette butt (ng h−1) at 0h, 2h, 5h. (a) styrene, (b) 2-methyl 2-cyclopenten-1-one, (c) naphthalene, (d) triacetin and (e) nicotine. Error bars show one standard deviation for data with 18 butts, and relative percentage difference for data with 27 butts.
