Coal fires are underground fires that burn in coal seams, often ignited by natural causes or human activities. These fires can smolder for years or even decades, producing smoke and harmful gases. They can occur in abandoned coal mines or in areas where coal is exposed to the surface. The environmental impact of coal fires is significant, as they release carbon dioxide and other pollutants into the atmosphere. Additionally, they can cause land subsidence and damage to ecosystems. Notable examples of coal fires include the Centralia fire in Pennsylvania and the Jharia coalfield in India.