How clear garbage bags reduce municipal waste by 27%

Intervention · Environment


From Texas-sized trash islands in the Pacific to your local landfill, failure to deal with our waste properly is leading to ecological devastation. We often throw everything - even things that could be recycled - in the garbage. To combat this tendency, researchers in Halifax observed the effects of a Clear Bag Policy. It dictated that citizens must use a clear plastic bag for their trash, which would be rejected if it contained recyclable materials. They found the Clear Bag Policy reduced municipal waste by nine tonnes per week, and boosted recycling rates by three percent.


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Rating: 4/5 (Easy to implement; moderate effects)

How a Clear Bag Policy Helped Halifaxians Waste Less and Recycle More
Opaque garbage bags
  • 50% Refuse Rate
  • 17% Recycling Rate
  • 97 Tonnes/Week of Waste
Clear garbage bags
  • 41% Refuse Rate (-9%)
  • 20% Recycling Rate (+3%)
  • 89 Tonnes/Week of Waste  (-9 tonnes/week)

Key Concepts

Green Nudges: Created by Richard Thaler, green nudges are a form of nudge that are designed to make an environmentally sustainable action more attractive. Typically, this involves changing the environment to make the green option the default, such as making not recycling less convenient than simply recycling with the Clear Bag policy.

Social Norm Bias: Studied since at least 1936, this bias reflects our desire to follow our society’s norms. If we feel and see that everyone around us does not recycle, we will be inclined to not recycle as well. In this case, since clear bags allowed Haligonians to see that everyone around them does recycle, they were more likely to recycle.

The Problem

Over the past thirty years, the amount of garbage we have collectively thrown away has grown at a rapid rate. Year after year, we buy more stuff, and subsequently throw it away. Unfortunately, the majority of this waste ends up in our oceans, wildlife, and even our food. Apart from denigrating the environment, this level of trash disposal also has caused local governments and citizens to undertake substantial management costs.

Plastic is the main culprit in this environmental challenge. While recycling is designed to deal with this issue, many people don’t bother to sort their waste, and simply throw everything out in one bag. Plastic, as it is lightweight, is blown from landfills into natural environments, leading to pollution. Unfortunately, not sorting your garbage is easier than meticulously sorting through all of it. Therefore, a behavioral intervention was necessary to make sustainable plastic disposal easier.


The Clear Bag Policy

The Clear Bag Policy was a top down, universally applied garbage disposal project that dictated residents were allowed to dispose of six clear plastic bags every two weeks. The idea behind the clear bags was twofold:

  1. To allow garbage collectors to instantly scan and see if there were any materials that could be recycled in the garbage. If so, the garbage collectors would refuse to take the bags.
  2. To allow the rest of the community to see who was recycling and who was not.

The nudge

The green nudge, in this sense, relied on moral pressure. While you were free to try to dispose of your recycling by mixing it in with your garbage, you would both incur the inconvenience of the collectors not picking it up and the disapproval of your eco-conscious neighbors.

This technique is similar to aspects of the CRI2SP framework, the EAST Framework, and the MINDSPACE framework, as they all emphasize creating environments where social norms and factors entice individuals to act in a more socially conscious manner.

The plan of action

The researchers set out to examine the effectiveness of this green nudge by comparing the total amount of waste, recycling, and refusal amounts before and after the Clear Bag Policy was implemented. Looking at five subsections of the municipality of Halifax, they also attempted to observe if there were any heterogeneous effects of the waste policy, meaning different communities experience different results from the intervention. Given that the Clear Bag Policy was implemented so quickly, this real world intervention provided a perfect experimental environment. As the citizens had little time to adjust to the new policy, it was clear that the effects were caused by this policy alone, and not simply changing attitudes over time.

Results and Application

Results: 9 tonnes of trash saved per week

Overall, it is clear that the green nudge led to both an increase in recycling, and an overall reduction in waste produced. From 2014 to 2017, total municipal waste dropped from 97.252 tonnes per week to 88.947 tonnes per week. Concurrently, we can see that the recycling rate increased from 17.4% to 20.2%. Clearly, a behavioral intervention was key in achieving the difficult challenge of reducing municipal waste. Furthermore, it did this without changing the number of bags allowed each week, charging higher taxes or new fees.

Can we nudge closer to saving the world?

While this intervention has been shown to be already effective in the real world, this intervention is incredibly promising for the future of climate change action. Currently, our lifestyles are often unsustainable. Apart from our excessive waste, our water consumption, fuel use, and diets have been proven to have disastrous side effects for the health of our planet. It has been long written off as too difficult and costly to shift these fundamental behaviors; however, this intervention proves that through gentle nudges, we can change unsustainable behaviors on a massive scale, which will no doubt be an effective tool in addressing climate change.

Related Applications

Climate & Energy Other municipalities and governments could easily implement a similar clear bag policy: it is relatively cheap, and they usually already have jurisdiction over waste collection.
Public Policy Some studies argue that informing an individual’s neighbors about their voting record (when legal) might increase voter turnout due to fear of disapproval.
Health & Wellness Studies suggest that transparent food packaging might lead to less snacking and over-consumption, as it makes consumers more aware of how much they are eating.


  • The intervention was demonstrably effective, but safety (e.g., risk of illegal waste disposal) was only briefly mentioned.
  • Data comes from a private municipal database, so it is unclear whether privacy or consent were respected.
  • Impact on different socio-economic groups is clear; impact among other demographic lines is less clear.

Does the intervention demonstrably improve the lives of those affected by it?
The intervention was effective at increasing recycling rates (by 3%) and decreasing waste (by nine tonnes per week)
Does the intervention respect the privacy (including the privacy of identity) of those it affects?
Insufficient Information
Data came from private administrative data from the Halifax government, so it is unknown whether privacy was respected when gathered.
Does the intervention have a plan to monitor the safety, effectiveness, and validity of the intervention?
Room for Improvement
Effectiveness was monitored through quantitative metrics. While safety and validity are discussed (e.g., whether the nudge might have driven some to illegal garbage disposal), no quantitative or qualitative metrics were used.

Does the intervention abide by a reasonable degree of consent?
Insufficient Information
The data comes from private administrative data from the Halifax government, so it is unknown whether it was collected in a consensual manner.
Does the intervention respect the ability of those it affects to make their own decisions?
Halifax residents were given a way to opt out of the policy: by purchasing their own garbage bins and bags, and disposing of it on their own.
Does the intervention increase the number of choices available to those it affects?
Not applicable
The intervention did not affect the number of choices Halifaxians had available to them.

Does the intervention acknowledge the perspectives, interests, and preferences of everyone it affects, including traditionally marginalized groups?
Room for Improvement
While the researchers considered how the policy worked in both high and low income areas, they did not consider whether the nudge unfairly affected some marginalized groups in other ways.
Are the participants diverse?
Room for Improvement
The participants are diverse socio-economically, but no data is provided as to whether they are diverse in other ways.
Does the intervention help ensure a just, equitable distribution of welfare?
Room for Improvement
While mitigating climate change is an equity issue, the researchers do not discuss any further ways this intervention might promote equity.

Related TDL Content

TDL Perspectives: Addressing The Climate Crisis: In this piece, Senior Consultant Jayden Rae and Managing Director Sekoul Krastev discuss the climate crisis, and what organizations like The Decision Lab can play in mitigating future disaster. Topics discussed include the collective action issue, the role of framing in effective climate policy, and behavioral issues in future thinking.

Reducing Water Consumption: Why You Care What Your Neighbours Think: In this piece, TDL’s Kit Slatford tackles another growing household environmental issue: water consumption. Twin trends of increasing water consumption and increasing water scarcity need to be combatted, and behavioral science may be the answer for this reckless consumption. Slatford explains how we can use personalized nudges to solve this problem and help our environment.


Akbulut-Yuksel, M. & Boulatoff, C. (2021). The Effects of a Green Nudge on Municipal Solid Waste: Evidence from a Clear Plastic Bag Policy.Journal of Environmental Economics and Management,forthcoming. Retrieved from

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