Brick kilns across India: A temporal analysis of brick kiln distribution and technology types

Abstract

Thousands of brick kilns operate across India, significantly contributing to air pollution and CO 2 emissions due to outdated practices and non-compliance with environmental standards. Regulations promoting cleaner kiln technologies have been introduced, yet detailed information on the spatial distribution and technology types of kilns remains limited. Effective and nationwide monitoring of kiln location and type is needed to mitigate their environmental impact. This study presents the first nationwide multi-year maps of brick kilns in India from 2019 to 2025, generated using Sentinel-2 imagery and a deep learning-based semantic segmentation model. The model incorporates a tailored loss function to reduce class confusion during training and thus improve type discrimination. To support model development and ensure transferability, we created MuTBriK , an open nationwide dataset containing 10,480 Sentinel-2 images covering 20,356 km 2 and representing five kiln types: Fixed Chimney Bull’s Trench Kiln (FCBTK), Zigzag, Circular BTK (CBTK), Roofed BTK (RBTK), and Down Draught Kiln (DDK). The model achieves a detection accuracy of approximately 93% on the test partition of the dataset and is subsequently applied to generate nationwide multi-year brick kiln maps. The resulting multi-year maps allow the quantification of changes in kiln distribution and technology. Together, the proposed mapping framework and dataset provide a reproducible basis for monitoring brick kiln distribution and technological transitions using openly available satellite data, supporting environmental assessment and emission-mitigation efforts.