India’s brick kiln industry has been mapped nationwide for the first time, giving researchers and regulators a detailed picture of where kilns are located and how their distribution has changed over time.
The multi-year study, published in the International Journal of Applied Earth Observation and Geoinformation, mapped brick kilns and their technologies between 2019 and 2025 using satellite imagery. The research was carried out by scientists from IIT Bombay and universities in Germany, Denmark and France.
India is the world’s second-largest brick producer, with more than one million kilns operating across the country. Uttar Pradesh has the largest concentration, followed by Bihar, while Rajasthan, West Bengal, Assam, Punjab and Haryana also account for significant numbers.
Researchers used freely available Sentinel-2 satellite imagery along with a deep-learning semantic segmentation model to identify and classify different types of kilns. The resulting maps provide information on the geographical and temporal distribution of the facilities.
The study said accurate information on kiln locations is important for assessing their contribution to air pollution and carbon emissions and for monitoring the transition towards cleaner production technologies.
Around 60% of India’s brick kilns are located in the Indo-Gangetic Plains, where strong construction demand coincides with the availability of alluvial clay suitable for brickmaking. Although concentrated in the region, emissions from the kilns can affect air quality well beyond their immediate locations.
Brick manufacturing is a significant source of pollution because of the continued use of older production technologies and uneven compliance with environmental regulations. The sector is estimated to account for about 15% of particulate matter emissions and 6% of carbon dioxide emissions, along with significant emissions of sulphur and nitrogen pollutants.
The researchers said India’s rapidly expanding urban areas and construction activity have helped drive the industry to more than one million kilns. Together, the kilns consume an estimated 35 million tonnes of coal and 25 million tonnes of biomass each year.
Many facilities are located in rural areas and along riverbanks, close to clay deposits. Their emissions can be transported towards nearby urban centres, making brick kilns an important district-level source of PM2.5 and black carbon, particularly across the Indo-Gangetic Plains.
Recent satellite-based emissions inventories have similarly identified brick kilns among the major district-level contributors to particulate pollution in the region. The researchers said the new nationwide database could help improve the accuracy of such assessments.
The study found that the location of kilns is largely determined by two factors — access to raw materials and local construction demand. This explains the concentration of kilns in sparsely populated rural areas and along riverbanks where clay-rich alluvial deposits are readily available.
India has also attempted to push the industry towards cleaner technology. In 2017, the Central Pollution Control Board mandated the conversion of traditional Fixed Chimney Bull’s Trench Kilns to zigzag designs. The latter can reduce energy consumption by around 20-30% and substantially lower harmful emissions.
However, the transition has been uneven, with enforcement varying between states. Researchers identified high initial investment requirements and limited awareness among kiln operators as additional barriers to the adoption of cleaner technology.
The study said the sector’s substantial energy consumption and emissions make the shift towards cleaner production increasingly important, but progress has remained slow because of financial constraints, lack of awareness and weak enforcement.
The researchers have made the resulting GeoJSON maps publicly available. The data could be used by the Union environment ministry, state governments and pollution control boards to improve monitoring, plan inspections and track the adoption of cleaner kiln technologies.
