Highly pungent, bleach-like odor detectable at 0.02 to 3.4 ppm (mean = 0.08 ppm)

Highly irritating and corrosive to the eyes, skin, and respiratory tract; reacts violently with readily oxidized substances.

Chlorine is a severe irritant of the eyes, skin, and mucous membranes. Inhalation may cause coughing, choking, nausea, vomiting, headache, dizziness, difficulty breathing, and delayed pulmonary edema, which can be fatal. Exposure to -500 ppm for 30 min may be fatal, and 1000 ppm can be lethal after a few breaths. Chlorine is highly irritating to the eyes and skin; exposure to 3 to 8 ppm causes stinging and burning of the eyes, and contact with liquid chlorine or high concentrations of the vapor can cause severe burns. Chlorine can be detected by its odor below the permissible limit; however, because of olfactory fatigue, odor may not always provide adequate warning of the presence of harmful concentrations of this substance.

Chronic exposures in animals up to 2.5 ppm for 2 years caused effects only in the upper respiratory tract, primarily the nose. Higher concentrations or repeated exposure has caused corrosion of the teeth. There is no evidence for carcinogenicity or reproductive or developmental toxicity of chlorine in humans.

Chlorine is noncombustible but is a strong oxidizer and will support combustion of most flammable substances.

Chlorine reacts violently or explosively with a wide range of substances, including hydrogen, acetylene, many hydrocarbons in the presence of light, ammonia, reactive metals, and metal hydrides and related compounds, including diborane, silane, and phosphine.