The study looked at how coal changes during the extraction of coalbed methane (CBM) and found that as coal oxidizes at low temperatures, pores in the coal expand and connect, leading to the formation of fractures. Different types of coal have similar patterns of pore development during oxidation, but the temperature at which this occurs varies based on the coal's metamorphic degree. The researchers developed a new index to predict the likelihood of coal and gas outbursts during CBM extraction, showing that the risk increases as the oxidation temperature rises. For lignite coal, fire prevention measures should be taken at 90°C, while for bituminous coal, it should be at 130°C.