It is impossible to generalize how long it takes for formaldehyde to be excreted from the human body, and it may usually take about 3-4 days to be completely metabolized from the blood. The excretion time of formaldehyde in human body is related to the amount and concentration of formaldehyde inhaled and the high or low basal metabolic rate of human body. When the concentration of formaldehyde in the environment > 0.08/m3, it can be absorbed into the human body through the respiratory and digestive tracts, causing symptoms of poisoning. Most of the formaldehyde can be excreted through the respiratory tract after entering the human body. If the amount of inhaled formaldehyde is small, or if the allopathic detoxification treatment is performed immediately after inhaling formaldehyde, it can be completely discharged about 12 hours after inhaling formaldehyde. Due to the rapid metabolism of formaldehyde, in most cases, formaldehyde cannot be measured in the human body in about 3-4 days. Only a few patients with more basic diseases and slower metabolism, the formaldehyde in the body completely discharged time is relatively long, may take 1-2 weeks. Formaldehyde residual in the body, the human body damage is obvious, should be early out of the formaldehyde environment, breathing fresh air, while appropriate fitness, and keep the body immune function intact.