Personnel engaged in toxic and harmful operations should have regular physical examinations. The inspection interval should be divided into four levels according to the classification standard of occupational exposure of poisons, and the grade I dangerous poisons should be inspected once a year; Second-class dangerous poisons are inspected once every two years; Grade III and IV hazardous poisons are inspected once every three years. The observed (absorbed) substances found in physical examination are reviewed once every six months.