If you stay in a place with excessive formaldehyde for a long time, the following reactions will occur: 1. Mucous membrane irritation symptoms, usually the most common side effect is mucous membrane irritation, especially in the eyelid mucosa of the eye, the nasal mucosa in the nasal cavity and the digestive tract mucous membrane irritation in the oral cavity, there will be redness, swelling, heat, pain, irritation with a distinct burning sensation in the eye, a pins and needles sensation in the nasal cavity and a burning and searing sensation in the oral cavity. 2. In the gastrointestinal tract, nausea, vomiting, acid reflux, heartburn, regurgitation, etc., in the circulatory system, chest tightness, shortness of breath, palpitations, weakness, etc., and in the nervous system, transient unconsciousness, dizziness, headache, etc., are obvious side effects.