Numerous studies have shown that ice surface is actually coated by a thin layer of water even for temperatures below melting temperature. This quasi-liquid layer is relevant in the atmospheric chemistry of clouds, polar regions, glaciers, and other cold regions. We present new results of atomic force microscopy on pure ice, which suggests a thickness for this layer below 1 nm between -7 ºC and -2 ºC. We propose that in many cases previous authors have overestimated this thickness.