Improving worker conditions in Brick kilns in Bangladesh

Plain English summary of protocol

Background and study aims
Bangladesh’s ~7,000 brick kilns contribute substantially to air pollution, responsible for 11% of the country’s particulate matter, 22% of black carbon, and 17% of total annual CO2 emissions. In our earlier work, we developed an intervention, Zigzag 2.0 (ZZK2.0), an intervention offering kiln owners and operators low-cost training and technical support in kiln management and insulation. In a trial with 276 kilns in Khulna Division, 65% adopted the two most important components. Adoption led to 24% less coal use per 100,000 bricks, with 21% reductions in both CO₂ and PM2.5 emissions. At the request of the Ministry of Environment, Forest and Climate Change, icddr,b scaled the intervention across 1000 kilns in 2023-25.

Yet, brick kiln workers represent a particularly vulnerable population. Our past study also delivered information to owners on the importance of incentivising workers to adopt the technical practices, but it was found that owners did not take up these suggestions. A recent study also showed that about 70% workers reported a lack of personal protective equipment (PPE), exposing them to risk of burns, head injuries, eye irritation, and smoke inhalation. Most lack formal contracts and endure 12- to 16-hour shifts near 800°C chambers, often without shaded rest areas or safe water. Many are seasonal migrants trapped in debt-bondage arrangements, often bringing their entire families, resulting in a high child labor prevalence, estimated at 70% of kilns. These harsh work conditions cause highly elevated risks of dehydration, heat exhaustion, long-term health complications, and even death. At the same time, heat-related illness may lead to productivity losses for owners. Other trafficking indicators reported less commonly by workers include wage or benefits withholding.

The study aims to: 1. Measure uptake of different workplace improvement components and improvements in workplace infrastructure and practices (PPE availability, shaded rest areas, safe drinking water access, breaks during heat periods); 2. Evaluate impact on worker-reported occupational injuries, health outcomes, wage withholding and labor trafficking indicators, and well-being; and 3. Assess changes in physiological heat strain indicators (core body temperature, heart rate variability, hydration status).

Who can participate?
Brick kilns (owners) and kiln workers in Bangladesh.

What does the study involve?
The study will involve 200 brick kilns, which will be randomly assigned to either the intervention group (120 kilns) or the control group (20 kilns), with each kiln treated as a separate unit in the randomization process. The study will be implemented across Jashore, Jhenaidah and Satkhira in kilns where icddr,b has established working relationships through previous interventions. Eligible kilns are those that adopted the ZZK2.0 technical intervention in past projects with icddr,b. Intervention kilns will get an integrated training on worker conditions and improvements, as well as a refresher on the ZZK2.0 technical methods. Implementation teams will support kiln owners with planning and implementing the improvements in their kilns through the brick season. Control groups will only be surveyed at baseline and endline.

What are the possible benefits and risks of participating?
The possible benefits of participating are improvements in worker health and well-being, improved living and working conditions, improved occupational safety, and a reduction in workplace injuries, both for participants and other workers on participating brick kilns. If such benefits are associated with the intervention, a long-term benefit is that these practices may be scaled to other brick kilns in Bangladesh (or even across South Asia) to improve the health and well-being of kiln workers outside the study sample.

It is acknowledged that introducing changes to workplace practices and employment relationships carries potential risks, including the possibility of unintended negative consequences for workers, such as strained relationships with owners, reduced work opportunities, or retaliation. Risk mitigation measures include confidential reporting mechanisms for workers to raise concerns about negative impacts, regular monitoring by field staff trained to identify signs of adverse effects, established protocols for responding to reports of retaliation or harm, and a process for withdrawing kilns from the intervention if serious harms are identified.

Where is the study run from?
The study will be conducted in Bangladesh, where the implementing organization (icddr,b) will be running fieldwork. The study is collaboratively supervised by researchers at icddr,b, Stanford University (CA, USA), and University of Michigan (MI, USA).

When is the study starting and how long is it expected to run for?
November 2025 to July 2026

Who is funding the study?
Stanford University, USA

Who is the main contact?
Grant Miller, ngmiller@stanford.edu

Contact information

Prof Grant Miller
Public, Scientific, Principal investigator

Department of Health Policy, School of Medicine Stanford University
615 Crothers Way
117 Encina Commons
Stanford
94305-6006
United States of America

ORCID ID	0000-0003-3191-2558
Phone	1-650-723-2714
Email	ngmiller@stanford.edu

Dr Nina Brooks
Scientific

School for Environment and Sustainability
Dana Building
440 Church Street
Ann Arbor
48109
United States of America

ORCID ID	0000-0003-3409-5434
Phone	+1(734) 764-6453
Email	ninarb@umich.edu

Study information

Eligibility

Locations

Countries of recruitment

• Bangladesh

Study participating centre

Results and Publications

Study outputs

Editorial Notes

08/12/2025: Study’s existence confirmed by the Ethical Review Committee of icddr,b, Bangladesh.