Is there any formaldehyde on the wallpaper?

Yes, the smell of wallpaper is not only formaldehyde, but also harmful gases such as benzene and TVOC: the wallpaper is pasted after being treated by the wall base, and then pasted with glue. Everyone who uses glue has these things, and the smell of wallpaper decoration is made of glue. There is only a small amount of wallpaper. But it is generally not high.