Chronic formaldehyde poisoning will show the following symptoms: 1. Symptoms of mucous membrane irritation, such as conjunctiva, bulbar conjunctiva, cornea, nasal mucosa in the nasal cavity, oral mucosa in the mouth will show irritating pain, burning sensation, burning sensation, eyes will show watery eyes, etc. 2. Chronic formaldehyde poisoning will show symptoms of respiratory system, such as cough, coughing sputum, poor breathing, or cough with blood in it, etc. 3. The symptoms of chronic formaldehyde poisoning are a series of circulatory system symptoms, such as chest tightness, shortness of breath, precordial discomfort, palpitations, etc. 4, there are also symptoms of the nervous system, such as irritability, insomnia, dizziness, headache, and plant nerve dysfunction, all of which are symptoms of chronic formaldehyde poisoning.