The Supreme Court is re-evaluating the definition of India's Aravalli range, a crucial ecological area near the capital. A proposed new definition, potentially lowering the elevation threshold for hills to be included, conflicts with a 2010 expert-defined boundary. Environmentalists advocate for the earlier definition to protect the ancient mountain range's ecology and its role in mitigating air pollution in the National Capital Region, urging caution against development that could harm the environment.