Large Swiss Anti-Littering Study in Zurich: Targeted Measures Reduce Littering by a Third

In the multi-year 'Large Swiss Anti-Littering Study', the Swiss Competence Center Against Littering IGSU, together with the School of Applied Psychology FHNW, investigates which measures are the most effective against littering. 'The commitment of Swiss cities and municipalities regarding littering is significant,' says IGSU Managing Director Nora Steimer. 'However, until now there were no resources to objectively measure the impact of different measures. With our field experiments, we aim to provide cities and municipalities with a tool that shows when and where measures can be effectively and efficiently applied.' In the summer of 2025, 'picnic and recreational zones' were the first of three settings to be examined: Various anti-littering measures were tested over ten weeks at 26 public places in nine cities and municipalities in German and French-speaking Switzerland. The results of this first field experiment are promising: The measures used reduced littering in picnic and recreational zones by about a third. This positive effect persisted even two weeks after the removal of the measures.

Situational measures work particularly well.

The anti-littering measures were categorized as situational and awareness measures. Situational measures such as recycling stations, humorous messages on trash cans, or noticeable arrows pointing to trash cans influence people's behavior at the moment they decide on disposal. Awareness measures like informative posters or personal awareness conversations, on the other hand, generally strengthen people's problem awareness and influence their attitudes in the long term.

The first field experiments clearly show: The most significant impact came from situational measures. Particularly effective were conspicuous arrows next to trash cans or trash cans with humorous messages, recycling stations with the option to separate PET, aluminum, or residual waste, and trash cans with gamification elements. For the latter, people could throw in their waste and simultaneously vote for their favorite: 'Which animal do you prefer?', the poster might ask, with waste being thrown into 'Dog' or 'Cat' bins. These measures led to a reduction in littering by 31 to 38 percent.

Combination of the two types of measures is especially promising.

Awareness measures were also reliably effective, but somewhat less so than situational measures: Posters and the use of personal awareness conversations conducted by the IGSU ambassador teams as part of the field experiments reduced littering by 26 to 32 percent. However, the most effective was a combination of both types of measures: The simultaneous use of personal awareness conversations and trash cans with humorous messages led to a reduction in littering by 49 percent. This suggests the impact is amplified by combining both types of measures.

City of Zurich draws a positive balance.

'In collaboration with cities, municipalities, and schools, we have been employing both situational and awareness-raising measures for many years. Now we know that both types lead to a significant reduction in littering,' says Nora Steimer. 'Based on this, we can optimally plan our measures in picnic and recreational zones in the future to effectively and efficiently counteract littering.'

In addition to Chavannes-près-Renens, Bern, Geneva, Lucerne, Olten, Regensdorf, Romanshorn, and Yverdon-les-Bains, the city of Zurich also participated in the field experiments. Michael Ultsch, Head of City Cleaning in Zurich, sees the field experiment as a good opportunity to gain new insights for future anti-littering measures—for example, recognizing that the public sector must continually innovate new measures against littering because each action wears off over time. 'While such a field experiment poses an additional burden and deviation from the routine for the cleaning staff, our employees take pride in keeping 'their' city clean. Like the public, they are bothered by litter and gladly assist in anti-littering measures,' says Ultsch. Further field experiments will be conducted in 2026, this time in 'catering zones around take-aways.' In 2027, experiments are planned along 'cross- country roads.'

For more information about this and other studies, please visit: www.igsu.ch/research.

Media Contact
- Nora Steimer, IGSU Managing Director. Phone: 043 500 19 91, 076 406 13 86
Email: medien@igsu.ch
- Prof. Dr. Nina Tobler, Professor of Business Psychology at the School of Applied Psychology FHNW, Email: nina.tobler@fhnw.ch

Quotes from participating cities

Valerio Mascio, Head of Districts, Infra Cleaning, City of Bern:

'Bern is interested in initiatives like the 'Large Swiss Anti-Littering Study' because we find it important to raise public awareness about littering. We have the impression that the measures in the field studies were well-received, with most passers-by following the recommendations for waste disposal. We assume that the measures will have an even greater impact if regularly implemented.'

René Wernli, Head of Workshop, City of Olten:

'Olten spends about 60,000 francs annually on anti-littering campaigns. Therefore, we are often asked if they are effective. We hope this study will allow us to answer such questions more convincingly. Not only did the public react positively to the measures, but the cleaning staff also supported the field study, as the insights would ultimately ease their daily work.'

Ursula Bernhardt, City Councillor for Energy and Environment, City of Romanshorn:

'Within the framework of the field study, we were repeatedly approached by passers-by, indicating that the measures were noticed and raised awareness. The feedback was mostly positive. Yet, there were also critical voices, with some people finding certain elements overdone or unattractive. This shows the interventions made an impact and sparked discussions. We are confident the study will promote a more conscious use of resources and the environment and thereby lead to less littering over time.'

Clivia Lugt, Project Manager, City of Yverdon-les-Bains:

'This field study showed us that visible and original measures can promote the use of trash cans. It also clearly demonstrated the importance of clear communication about how measures work, especially when they deviate from usual disposal practices. The purpose and function of the 'voting bins,' for instance, were not always clearly understood. We hope the study contributes to evaluating the effectiveness of measures and improving the city’s future measures.'

Michael Ultsch, Head of Street Cleaning, City of Zurich:

'The field experiment is a good opportunity to gain new insights for future measures against littering: for instance, learning that the public sector has to keep inventing new measures against littering, as every action eventually wears out. Even though such a field experiment poses an additional effort and deviates from routine duties for the cleaning staff, our employees cherish keeping 'their' city clean. The staff, like the public, are bothered by piles of waste and are glad to contribute to anti-littering measures.'

IGSU
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8045 Zurich
Tel 043 500 19 99
info@igsu.ch
www.igsu.ch

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