The hazards of formaldehyde are as follows: First, the most common hazard is toxic effect, which will cause different degrees of damage to respiratory tract, digestive tract, circulatory system and nervous system. For example, respiratory tract injury is often accompanied by typical symptoms such as dyspnea, mucosal irritation, cough, expectoration, pharyngeal congestion and respiratory hypoxia. At this time, there will be clinical symptoms of gas poisoning such as hypoxemia, hypercapnia and decreased arterial oxygen saturation. Second, stimulating the digestive tract has different degrees of harm such as nausea, vomiting, anorexia, abdominal distension, diarrhea, and even bloody stool. Third, stimulating the circulatory system will cause chest tightness, shortness of breath, palpitation, precordial discomfort and other symptoms of insufficient myocardial blood supply. Fourth, it will cause nervous system tension, anxiety, insomnia, dizziness, headache and other hazards. There are several methods in in addition to formaldehyde: 1, opening doors, opening windows for fresh air and air circulation. 2. Activated carbon can be adsorbed in the room.