(1) Hazards are categorized into root hazards and status hazards. The root hazards are the root cause of accidents in coal mine, which are objective and inherent in the underground coal mining and production process regardless of being identified or not. The status hazards are the unsafe conditions or unsafe behaviors that can release or allow a root hazards to trigger an accident. Furthermore, the status hazards are further divided into identified status hazards and unidentified status hazards, and the identified status hazards include controlled and uncontrolled status hazards.