There are many reasons why boogers are black, including inhaling airborne pollutants and black crusts from nasal bleeding. 1. Pollutants in the air: If you live in a heavily polluted area, or are affected by the working environment, exposure to polluted air, industrial dust and other factors, resulting in the inhalation of dirty air, filtered through the nasal cavity, it is easy to appear boogers are black, in this case, the patient should pay attention to do a good job of the corresponding protective work, wear a mask, wash your hands diligently, and so on. 2. Nasal bleeding black crust: when the nasal cavity by dry, trauma and other stimuli, easy to appear capillary rupture bleeding, this time the blood coagulation leads to the nasal cavity black crust, should go to the hospital in time to clarify the cause of active treatment. The situation of black boogers, should go to the hospital in time for systematic examination, to exclude the possibility of bleeding, a clear diagnosis. At the same time, in daily life to do a good job of protection, keep the nasal cavity clean, eat more fresh fruits and vegetables.