Further information Description Chlorine is a greenish yellow gas which combines directly with nearly all elements.
Chlorine is a respiratory irritant.
The gas irritates the mucous membranes and the liquid burns the skin. As little as 3.5 ppm can be detected as an odour, and 1000 ppm is likely to be fatal after a few deep breaths. It was used as a war gas in 1915. Both values are quoted on the Pauling scale. For most elements, the most stable allotrope is illustrated.