Training brick manufacturers to reduce emissions in Bangladesh

The Problem

Brick manufacturing in Bangladesh is growing rapidly to fit construction needs, but emissions from the sector are threatening lives.

Brick manufacturing in Bangladesh is a fast-growing industry, with over 7,000 kilns producing around 33 billion bricks annually. The sector annually contributes roughly seventeen percent of the country’s CO2 emissions and eleven percent of its particulate matter pollution.¹ Particulate matter consists of small airborne particles that people can inhale, and that can damage respiratory and cardiovascular health. Bangladesh is currently one of the most polluted countries in the world. On average, particulate matter air pollution shortens life expectancy by 6.8 years in Bangladesh; pollution from brick kilns alone causes an estimated 6,000 premature adult deaths each year.^2,3

Across the country, many residents are exposed to local pollution from brick kilns. During the brick firing season, people living within two kilometers of a kiln are exposed to local air pollutant levels five times higher than WHO guidelines. Adverse health impacts have been observed as far as eight kilometers downwind from a single kiln, and fifty kilometers downwind from multiple kilns.⁴

Many brick manufacturers in Bangladesh operate in the informal economy, making their pollution hard to regulate. Although policies restrict kilns from operating near population centers (e.g., within one kilometer of a school), these regulations are weakly enforced at best, and informal kilns that are shut down after violating these policies can reopen within months.⁵ Brick kilns also rely heavily on adult labor trafficking and child labor, driven in part by seasonal migration of vulnerable populations seeking work, and provide unsafe working conditions. 

The Ministry of Environment, Forest, and Climate Change (MOEFCC) has worked over three decades to shift the industry toward cleaner modern kilns, but these kilns make up less than two percent of all kilns in Bangladesh. Because the modern kilns are expensive to establish, they require access to large-scale, formal credit, making it challenging for existing manufacturers to switch.⁶ For these reasons, the informal, coal-fired kiln industry continues to operate at a massive scale. 

In this context, researchers identified an opportunity to reduce emissions in the near term by training informal brick kiln owners and staff to operate kilns using less coal. Because these practices were voluntary and allowed kiln owners to spend less on coal, they were better suited to be adopted quickly, especially in the informal sector where regulation is challenging. 

The Research

Researchers trained owners and operators of informal brick kilns in fuel-efficient practices that reduced both local air pollution and CO2 emissions. These practices also lowered kiln costs, motivating kiln owners and operators to continue using them. 

J-PAL researcher Stephen Luby (Stanford University) has worked with local public health organization the International Center for Diarrhoeal Disease Research, Bangladesh (icddr,b) for over 18 years to address Bangladesh’s air pollution crisis. They found that 81 percent of kiln operations in Bangladesh use a traditional kiln type called the zigzag kiln which, when operated correctly, is more efficient than older style kilns. However, most build and operate them incorrectly, diminishing efficiency. 

After testing multiple other methods, the team worked with engineering consultancy Greentech Knowledge Solutions to develop a simple set of low-cost, coal-saving practices that could be taught to brick kiln owners and operators. The practices in the training, referred to as Zigzag 2.0, include continuously feeding coal into the kiln (rather than feeding larger, infrequent batches) and stacking bricks in a way that increases airflow. In testing, they were shown to decrease emissions and increase productivity.

To test whether the trainings reduced pollution in the real world, researchers acquired government permission to introduce the training in Jashore district in Khulna Division of Bangladesh in 2021-2022. The team included J-PAL researchers Stephen Luby (Stanford University), Nina Brooks (Boston University), Grant Miller (Stanford University), and Aprajit Mahajan (University of California, Berkeley), and icddr,b researchers Debashish Biswas, Mahbubur Rahman, and M. Rofi Uddin. Icddr,b worked with the professional organization for brick manufacturers in the area, the Bangladesh Brick Manufacturing Owners’ Association (BBMOA), to expand outreach and trust among kiln owners, increasing their willingness to participate in the trainings. The Bangladesh University of Engineering and Technology (BUET) supported this intervention, and as a trusted technical partner to the Department of Environment (DOE), helped secure the permission to run the study.

Following a successful pilot, the research coalition conducted a randomized evaluation of Zigzag 2.0 with 276 kilns in Khulna Division from 2022 to 2023.⁷ Eighty-nine randomly selected kilns received the Zigzag 2.0 intervention alone, 95 kilns additionally received suggestions to improve working conditions or wages for employees, and 92 kilns served as a comparison group.

The Zigzag 2.0 intervention reduced CO2 and particulate matter pollution from brick firing by 20 percent.⁸ The practices required no additional capital investment and could be easily integrated into existing manufacturing practices. They also increased brick quality and reduced spending on coal, giving kiln owners economic incentives to adopt them. Combining the Zigzag 2.0 intervention with suggestions to either improve working conditions or increase pay did not improve conditions or pay for workers.⁹

Kiln owners rapidly adopted these practices, motivated by both economic benefits and visible signs of reductions in air pollution. The study also found that adoption increased from the first year to the second: by 2023, 74 percent of kilns trained during the evaluation had adopted the practices, compared to 65 percent in 2022. After the evaluation, the training was provided to kilns in the comparison group, and 57 percent of them adopted or continued using the practices in the second year.

This research received funding from J-PAL’s King Climate Action Initiative (K-CAI). To learn more, read the evaluation summary. 

From Research to Action

The Government of Bangladesh supported the Zigzag 2.0 intervention as part of its broader approach and approved the scale-up of J-PAL-evaluated trainings to achieve meaningful emissions reductions in the immediate term. 

After the research team presented its findings in mid-2023, the MOEFCC invited the team to scale up the intervention to kilns in Khulna and Dhaka divisions. The government recognized the Zigzag 2.0 trainings, which offer a way to cut emissions and pollution from informal kilns more immediately, as an important complement to its long-term plan to switch to higher-cost, modern kilns. K-CAI provided rapid-response funding to support the scale-up. 

To mobilize the scale-up before the kiln firing began in November 2023, the icddr,b team quickly adapted to a training load five times larger than during the randomized evaluation, without compromising quality.

The researchers and partners are working to scale the interventions to all traditional kilns in Khulna and Dhaka by 2026. Together, they aim to eventually reach all traditional kilns across Bangladesh, estimated at over 7,000 kilns. Since the scale-up began in November 2023, over 800 additional kilns have been trained in cleaner manufacturing practices, bringing the total to more than 1,000 kilns, including those trained during the pilot and evaluation. In Khulna, where kilns are distributed widely across the state, the intervention has improved air quality for Khulna’s large population of 17.5 million people.

In 2024, key elements of the training—such as altered brick stacking, changing coal feeding procedures, and increasing kiln insulation—were formally included in the Bangladesh National Air Quality Management Plan 2024-2030. Despite a change in government in 2024, the evaluation’s findings are still informing policies that aim to address pollution from informal kilns, with strong endorsement from the interim government.

The team is also working with J-PAL South Asia to explore partnerships to scale up the trainings to northern India. The research coalition has a long-term vision to reach the entire “Brick Belt” of South Asia, covering parts of Bangladesh, Nepal, Pakistan, and India, where over a quarter of global brick production takes place and traditional kilns dominate. The researchers continue to work with partners in Bangladesh on developing and testing interventions to reduce trafficking and improve working conditions in the brick manufacturing industry.

References

Brooks, Nina, Debashish Biswas, Sameer Maithel, et al. 2025. “Reducing Emissions and Air Pollution from the Informal Sector: Evidence from Bangladesh.” Science 388(6747). https://doi.org/10.1126/science.adr7394.

Brooks, Nina, Debashish Biswas, Raduan Hossin, et al. 2023. “Health consequences of small-scale industrial pollution: Evidence from the brick sector in Bangladesh.” World Development 170 (October). https://doi.org/10.1016/j.worlddev.2023.106318.

Lee, Jihyeon, Nina Brooks, Fahim Tajwar, et al. 2021. “Scalable deep learning to identify brick kilns and aid regulatory capacity.” Proceedings of the National Academy of Sciences of the United States of America 118 (17). https://doi.org/10.1073/pnas.2018863118.

Miller, Grant, Debashish Biswas, Aprajit Mahajan, et al. “Productivity Gains and Work Conditions in Coercive Labor Markets: Experimental Evidence from the Bangladesh Brick Sector.” NBER Working Paper 32829, October 2025. https://www.nber.org/papers/w32829.