Bangladesh is one of the most polluted countries in the world. According to an IQ Air assessment, the country had the second-worst air quality in 2024 worldwide, with PM2.5 concentration more than 15-times the World Health Organisation’s suggested limit.

Brick kilns are a major contributor to this air pollution crisis. Previous efforts to improve the greenness of the local brick-making industry have resulted in limited success – but if a new study is to be believed, there is room for low-cost interventions to make a difference with these kilns.

Carefully crafted interventions

The study, published in Science on May 8, was conducted by researchers from the U.S., Bangladesh, and India. They performed a randomised control trial involving 276 kilns in Bangladesh, in the brick-firing season of November to May in 2022-2023.

The experiment had three parts: one control arm and two interventions. One intervention was solely technical and the other included both a technical intervention and incentive information.

The main idea behind the intervention arms of the trial was to reduce emissions, air pollution, and fuel costs while increasing revenue by increasing efficiency. While both arms provided information, training, and technical support on efficient coal feeding and brick-stacking practices, the incentive information arm also guided workers with incentives so that they stuck to their newly learned practices.

For the incentives, the researchers informed the kiln owners on various strategies like bonuses, higher wages, and better working conditions that included meals, housing, and clothing, but left it up to the owners and managers to decide which approach best fits their business.

The team also noted that the interventions were careful to not worsen the workers’ conditions in the industry, given the nature of work here is often precarious and exploitative.

The study was performed on zigzag kilns – a name that refers to the shape of the stacks in which these kilns arrange raw bricks, so that more hot air comes in contact with the bricks’ surfaces. This method improves heat transfer and increases brick firing efficiency, and is the dominant type of informal brick kiln operating in Bangladesh, accounting for 81% of the sector.

No effect of incentives

The researchers also noted that the operators of most of these kilns were receptive to the interventions and that 65% of the kilns adopted the recommended practices. Almost 20% of control kilns (another kiln type) also did so, attesting to the demand.

Curiously, the researchers reported that while there were no differences in the rates of adoption, the presence or absence of incentives didn’t have an effect either. This is in contrast to previous studies that found directly providing monetary incentives to workers could lead to better outcomes.

Among the compliant kilns, researchers noted a 23% reduction in energy use, a 20% reduction in both carbon dioxide and PM2.5 emissions, and better brick quality and lower fuel cost per brick. The intervention’s benefits outweighed its costs by 65:1, with carbon dioxide reductions costing $2.85 per tonne.

None of the interventions needed additional capital investment.

No rebound effects

The evidence of how efficient energy-related interventions are has been inconsistent in the past. However, the new study has presented substantial proof that carefully designed operational improvements can also lead to significant energy savings.

The five operational improvements the study focused on were: single fireman continuous fuel feeding, improved brick stacking, a thicker ash layer on kiln top, closing the kiln gate with a cavity wall, and complementary use of powdered biomass fuel. The idea behind these specific changes was that they improve fuel combustion and prevent loss of heat in the kilns.

Notably, the energy savings noted in the study were achieved without rebound effects, which usually negate the benefit by increasing energy use elsewhere. The absence of these effects makes a stronger case for these interventions, the researchers said.

The lower carbon dioxide and PM2.5 emissions observed during the trial experiment have important public health implications, especially for a country like Bangladesh. According to the researchers, if the project is scaled nationally and the interventions are adopted by all 6,352 zigzag kilns in Bangladesh, carbon dioxide emissions could be brought down by 2.4 million metric tonnes in a single brick-firing season – around 2% of the country’s annual emissions.

The researchers also expressed belief that their interventions can be scaled up across Bangladesh as well as South Asia – a region with a significant air pollution problem.

Brick production techniques are similar throughout most South Asian countries. Regulating energy efficiency is particularly beneficial in those regions where air pollution has become a serious problem as well as where energy demand is increasing rapidly. In these areas, state intervention has often proved an unreliable way to control emissions, especially in informal sectors.