After boiling water to remove formaldehyde for 5 hours, windows can be opened for ventilation. Just boiling water is not enough to remove formaldehyde. There is a small method. Close the doors and windows, prepare a basin of boiling water, pour a bottle of white vinegar into the water, boil it for 3 to 5 hours, and then open the windows for ventilation. This can remove part of the formaldehyde and purify it. Air problem just after renovation.