The main method of deep breathing self-examination of pneumothorax is to inhale deeply and then exhale slowly to feel whether the breathing of the left and right lungs is symmetrical. If the expiratory and inspiratory volumes of one lung are relatively reduced, it suggests that the possible pneumothorax is on this side. In addition, observe the chest wall on both sides during deep breathing, and if one side of the chest wall shows a weakening of the thoracic expansion during expiratory and inspiratory movements, consider that this side may have a pneumothorax. Use the palms of both hands to palpate the left and right side of the chest symmetrically while inhaling and exhaling deeply, and make an ah or yah sound, if one side of the chest tremor is weakened, it may be a pneumothorax site. If pneumothorax may exist in the initial screening, go to the emergency department immediately to take X-ray or CT of both lungs to clarify the condition and cause for timely treatment.