Formaldehyde can be very harmful to the human body, so it is important to understand what the dangers of formaldehyde are. First, formaldehyde can cause acute poisoning and great damage to the skin. When formaldehyde reaches a certain level, the human body will experience uncomfortable symptoms, such as hoarseness, itchy eyes, throat discomfort, dermatitis, breathing difficulties, and in serious cases, it can cause pulmonary edema, anaphylaxis and liver failure. When inhaled in excess, it can lead to death. Formaldehyde can also cause leukemia, mainly because it causes mutations in human genes, produces damage to human hematopoietic function, and has a very strong carcinogenic effect. Therefore, it must be noted that when the concentration of formaldehyde is relatively high, it must be ventilated indoors, or buy air filters, which can effectively slow down the harmful effects of formaldehyde.