Formaldehyde will mainly cause allotriosmia, irritancy, allergy, lunge and immunologic function abnormal. Human can feel abnormal smell and uncomfortable when Formaldehyde content reaches to 0.1 mg/m3,iritating with eye watering when 0.5 mg/m3, throat uncomfortable and hurt when 0.6 mg/m3, nausea, emesia, cough, chest stuffing, asthma,even emphysema pulmonum when the concentration is higher. If staying in Formaldehyde at low concentration, people will feel headache, feeble sensory disturbance with the two sides asymmetric and sight disturbance,and it will restrain sweat glands and cause the skin dry and wrinkle. When the concentration is higher, it will irritate mucous coat, upper air tube,eyes and skin and do harm to nervous system, immune system and hepar.

People started to study the relation between Formaldehyde and cancer since 1980s, where the carcinogen of Formaldehyde is approved in animal experiment. However, it is not concluded yet whether it will be a carcinogen to human being through comparison at home and abroad. It reported that it may have some relation to nasopharyngeal darcinoma.MOSH has listed Formaldehyde as suspicious carcinogen to human body.WTO work group has defined the threshold value of its potential carcinogen to olfactory sensation, eye and air tube iritancy, and warns that it should be paid enough attention to when the concentration of Formaldehyde is above 10% in indoor environment.