If the mothballs if smelled for more than three months will be poisoned. Mothballs are a kind of organic matter extracted from petroleum or coal tar, it is benzene poisoning as the main poisoning situation of smelling mothballs. Benzene poisoning will occur when the respiratory system of coughing, dyspnea, respiratory depression, etc.; digestive system will appear nausea, vomiting, accompanied by abdominal pain, diarrhea, dilute watery stools, etc.; circulatory system will appear chest tightness, shortness of breath, palpitations, precordial discomfort, accompanied by weakness, etc.; in the nervous system there will also be a neurasthenia, dizziness, headache, disorientation, orientation disorder, etc.. So mothballs can not be smelled for a long time, if a long time to smell mothballs for more than three months, there are the above symptoms must be immediately consult a doctor.