Applying social research to understand the dynamics driving plastic bag use in Indonesia’s traditional markets – and how to change them.

In 2018, Bali’s provincial government passed a bold regulation to ban specific single-use plastic (SUP) items across the island. The law has heavily targeted modern stores and retailers, with less attention paid to traditional markets where many local people continue to shop daily for fresh produce. 

Case in point, in 2019 we observed that of the roughly 260 customers entering a traditional market in Denpasar every hour, only 19% brought reusable bags, while continuing to be supplied with plastic bags by sellers.

Catalyze is lucky to call Bali, the “Island of Gods”, as home. Over the years, several of us have invested countless hours in efforts to reduce plastic pollution here. We saw traditional markets as a tantalizing challenge to apply a systems design approach to further chip away at the plastic ‘tsunami’.   

What do we mean by a systems approach? A system consists of a connected set of elements — people, cells, molecules etc — that produce their own pattern of behaviour. Designing or redesigning a system means working at the intersection of these elements to achieve an outcome. 

Markets are an ideal system to work with: their boundaries are relatively well defined, and their main elements and the interconnections between them can be identified relatively easily.

This was our approach:

During the Identify stage, we focused on analysing all interconnections of each element (money, sellers, goods etc.) in the system. This involved assessing what inputs were driving the use of SUP bags through stakeholder discussions, and assessing past efforts (historical tracking and mapping).

We also reached out to the management of the traditional market to introduce our approach. Sellers, the key users in this challenge, were involved in those early conversations. Based on their feedback, we defined an approach to explore possible solutions to reduce SUP, before testing them out in the market.


A major pain point in the process of reducing SUP bags is alternatives. This is tricky because traders in traditional markets are highly price-sensitive, so if an alternative is introduced it needs to be if not cheaper, at least comparable in price to SUP bags.

This made the next step, Prototyping, a gruelling process. Our team designed reusable bags using post-consumer newspapers, and a series of posters. Sellers did not warm up to the bags, despite the fact that before SUP bags became the norm, they were using this type of packaging solution. Size and thickness affected sellers’ interest, and in the end the design that was the most practical came with a price tag that was twice that of a SUP bag – a dead end in terms of acceptability by sellers.

The posters were relatively better received. We used a social proximity strategy in developing them, by showing the seller's face in each one (as in the photo). According to the spices sellers who collaborated with us, these posters sparked customers’ curiosity, creating opportunities to discuss the issue of plastics. Sellers also seemed attached to these posters.

Throughout the design process, our approach evolved regarding how to interact with stakeholders in the market. We shifted our strategy from bottom-up to top-down when we rolled out our intervention with the bags and posters, partly as a result of realizing the significant role of the market management in applying a new system.

In our last post-intervention assessment, we recorded an increase in reusable bags usage by customers (from 33.9% to 47.5%), a modest but appreciable improvement. We are aware that this increase cannot be solely attributed to our intervention, as aside from our efforts the government has continued to raise awareness of the SUP ban, and various other programmes from other communities across Denpasar continued to be rolled out.

With a small team and no significant resources, our research and design efforts made it possible to influence some key interconnections in the traditional markets system: sellers x bags, money x bags, management body x sellers, among others. Taking these efforts to achieve systemic change would require more time and experimentation – but it has certainly opened our eyes to the merits of a systems framework to reducing excessive use of SUP in these overlooked places.