US scientists studying satellite data have discovered an immense wintertime pool of pollution over the northern Indian state of Bihar. Blanketing around 100 million people, primarily in the Ganges Valley, the pollution levels are about five times larger than those typically found over Los Angeles.
The discovery was made by researchers analyzing four years of data collected by the Multi-angle Imaging Spectro-Radiometer (MISR) onboard the Terra satellite. Lofted into orbit on Dec. 18, 1999, Terra is the flagship of NASA’s Earth Observing System Program.
While high pollution levels were found over much of India, a concentrated pool of particles was discovered over Bihar, a largely rural area with a high population density. A large source contributing to the Bihar pollution pool is the inefficient burning of a variety of biofuels during cooking and other domestic use. Particles in the smoke remain close to the ground, trapped by valley walls, and unable to mix upward because of a high-pressure system that dominates the region during winter.