Formaldehyde is a volatile and toxic gas, and its poisoning can be acute or chronic. In the case of acute poisoning, the respiratory system is usually affected first, with dry and painful mucous membranes in the mouth and nose or an irritating cough, which may also trigger the appearance of asthma. If it causes laryngeal edema, there will be difficulty in breathing. Secondly, it affects the central nervous system, resulting in dizziness, headache, nausea, vomiting, and in severe cases, coma, shock, or even central respiratory depression leading to life-threatening effects. If the volatile toxic gas irritates the skin, symptoms of generalized urticaria will appear, such as a generalized papular rash or a rash like a windbreak, usually with itching as the main symptom. If there is a chronic poisoning of formaldehyde, there will generally be symptoms of neurasthenia, such as frequent insomnia, dreaminess, lack of concentration, and in severe cases, the hematopoietic system will be affected, resulting in chronic anemia, with generalized skin pallor and other manifestations, and in the most serious cases, some symptoms of leukemia will appear.