Formaldehyde characteristics: long time to volatilize, formaldehyde release cycle up to 3-15 years. Formaldehyde is hidden in all kinds of furniture and decorative materials, and is only emitted to the indoor air under certain temperature and humidity. By its heating period and early spring season, indoor generally all closed, air does not flow, resulting in higher and higher concentration of indoor formaldehyde. Irritation reaction: manifested as eye and upper respiratory tract irritation symptoms, no positive lung signs, no abnormal findings on chest x-ray examination. Diagnosis and grading criteria: (1) Mild poisoning with one of the following conditions: a) with obvious symptoms of eye and upper respiratory tract mucous membrane irritation, signs of conjunctival congestion, edema, coarse breath sounds in both lungs, and may have scattered dry and wet stalls with increased and thickened lung texture on X-ray examination. The above performance is consistent with acute trachea a bronchitis; b) one to two degrees of laryngeal edema. (2) Moderate poisoning with one of the following conditions: a) persistent cough, sputum, chest tightness, dyspnea, scattered dotted or small patchy shadows on X-ray examination of both lungs with dry and wet stalls. The above manifestations are consistent with acute bronchopneumonia; b) third degree laryngeal edema. Blood gas analysis is mild to moderate hypoxemia. (3) Severe poisoning with one of the following conditions: a) pulmonary edema; b) fourth degree laryngeal edema. Blood gas analysis is severe hypoxemia. Treatment of poisoning: Observe those with upper respiratory tract irritation for at least 48 hours to avoid aggravation after activity. Those exposed to high concentrations of formaldehyde can be given 0.1% light ammonia inhalation; early, adequate and short course of glucocorticoids can effectively prevent laryngeal edema and pulmonary edema. Keep the airway open: give bronchial antispasmodics, defoamers, and perform tracheotomy if necessary. Reasonable oxygen therapy. Treat symptomatically to prevent infection and prevent complications. Other treatment: after treatment of mild and moderate poisoning, after short-term rest, you can generally engage in the original work; however, those who are allergic to formaldehyde should be transferred away from the original work; depending on the recovery of the disease, arrange for non-exposure to toxic work as appropriate for severe poisoning. The following ways are recommended to prevent formaldehyde poisoning: (1) Improve indoor ventilation equipment and purchase indoor air purifiers. (2) Plant potted plants, aloe vera, cactus and other green plants. (3) The use of aromatic substances or the placement of fruits, vegetables, etc., can only cover the smell of formaldehyde, can not be removed. (4) all kinds of sprays to remove formaldehyde, short duration, volatile that is lost, easy to cause secondary pollution.