For the first time, the locations of brick kilns across the country have been mapped, providing nationwide data to track their contribution to air pollution and carbon emissions.
The study, published in the International Journal of Applied Earth Observation and Geoinformation, was conducted by 10 researchers from the Indian Institute of Technology Bombay (IIT Bombay), the University of Münster and the University of Rostock in Germany, the University of Copenhagen in Denmark, and Université Paris-Saclay in France.
India is the world’s second-largest brick producer, with more than a million kilns. Uttar Pradesh accounts for the highest number, followed by Bihar, while Rajasthan, West Bengal, Assam, Punjab and Haryana are among the other states with large numbers of kilns.
The multi-year satellite maps documented the locations and technologies of these kilns between 2019 and 2025.
The sector contributes significantly to air pollution and carbon emissions due to outdated practices and non-compliance with environmental standards, accounting for an estimated 15 per cent of particulate matter and 6 per cent of carbon dioxide emissions, in addition to significant quantities of sulphur and nitrogen pollutants.
Researchers used freely available Sentinel-2 satellite imagery combined with a deep-learning semantic segmentation model to classify kiln types. “Precise knowledge of the spatial and temporal distribution of brick kilns is essential for evaluating their contribution to air pollution and carbon emissions, and for assessing progress toward cleaner production technologies,” they said.
Geographic analysis showed that about 60 per cent of the kilns are located in the Indo-Gangetic Plains, where high construction demand coincides with abundant alluvial clay deposits. However, their environmental impact extends beyond the region, affecting air quality across the country, according to the study.
Recent earth-observation-based emission inventories have identified brick kilns as among the leading district-level sources of particulate matter over the Indo-Gangetic Plains, underscoring the value of accurate and up-to-date kiln location data. Emissions affect workers and local air quality, while long-range atmospheric transport further contributes to pollution in nearby urban centres.
According to the researchers, rapid urbanisation and construction activity have driven the industry to more than a million kilns across India, which burn roughly 35 million tonnes of coal and 25 million tonnes of biomass every year.
Many of these facilities are located along riverbanks or in rural areas, with emissions drifting into nearby cities and making kilns a primary source of district-level PM2.5 and black carbon.
The study found that the spatial distribution of brick kilns is primarily driven by the availability of raw materials and regional construction demand. As a result, kilns are predominantly located in rural, sparsely populated areas or along riverbanks, where clay-rich alluvial deposits are accessible.
In 2017, the Central Pollution Control Board mandated a transition from traditional Fixed Chimney Bull's Trench Kilns to cleaner zigzag designs, which reduce energy consumption by 20 to 30 per cent while substantially lowering harmful emissions. However, enforcement remains patchy across states, while high upfront costs and limited awareness among operators have slowed the transition.
“Given the sector’s high emissions and energy demand, there is a pressing need for cleaner and more sustainable brick production technologies. However, the shift to cleaner brick production is slow due to high initial costs, lack of awareness, and weak enforcement of regulations,” the study observed.
The union environment ministry, state departments and pollution control boards now have access to the open GeoJSON maps, which could be incorporated into future inspection strategies.
