First aid is the immediate and temporary care provided to an injured or suddenly ill person before professional medical treatment becomes available. In mechanical and electrical work environments, first aid is particularly important because workers may be exposed to electric shock, electrical burns, thermal burns, cuts, fractures, crushing injuries, eye injuries, chemical exposure, falls and other industrial accidents. The primary objectives of first aid are to preserve life, prevent the condition from becoming worse, promote recovery and arrange appropriate medical assistance. First aid should be provided quickly, calmly and systematically while ensuring that the rescuer does not become another casualty. The first principle of first aid is to ensure the safety of the scene. A rescuer must identify and control continuing hazards before approaching the injured person. In an electrical accident, the victim must not be touched while still in contact with an energized conductor because the rescuer can also receive a fatal electric shock. The electrical supply should be isolated by switching off the main supply, circuit breaker or disconnecting device whenever this can be done safely. If isolation is not immediately possible, only appropriate insulated rescue equipment and procedures should be used by a trained person. In mechanical accidents, moving machinery must be stopped and secured before attempting rescue. Sources of fire, chemicals, falling objects, compressed air and other hazards should also be controlled. After making the area reasonably safe, the rescuer should assess the victim's condition. The basic assessment includes checking responsiveness, breathing and signs of serious bleeding. If the person is unconscious and not breathing normally, emergency medical assistance should be activated and cardiopulmonary resuscitation should be started by a trained rescuer. An automated external defibrillator, if available, should be used according to its instructions. If the victim is breathing but unconscious, the airway must be protected and the person should be