Cigarette butts are the world’s most widespread form of litter, with 45 billion discarded every year. In Malmö, Sweden’s third-largest city, littering costs taxpayers 6 MEUR annually, and half of that amount is spent on cleaning up cigarette butts. To change smokers’ behaviour and reduce littering, there was a need for clear communication about where to dispose of them.

Instead of relying on prohibitions and warnings, we chose to guide behaviour more directly. We revived one of humanity’s oldest forms of communication, smoke signals, and adapted it to an urban environment. The installation used rising smoke to signal where smokers should go to smoke and dispose their cigarette butts. Meanwhile, smokers became part of the system, as each correctly discarded cigarette contributed to the signals. The solution turned individual actions into visible communication, creating a continuous loop, driven by behaviour.

The proportion of smokers who disposed of their cigarette butts in ashtrays instead of on the ground increased from 27% to 63%, more than doubling the behaviour and representing an increase of +144%. The initiative was picked up across social and news media, reaching over 23 million people.