What is chlorine?

Chlorine is a naturally-occurring element that can be either a gas or a liquid. As a gas, chlorine has a yellow-green color and a strong, irritating odor similar to bleach. Chlorine can be converted to a liquid at very cold temperatures for shipping. If the liquid is released, it quickly turns into a gas. Chlorine gas can be released if household bleach mixes with ammonia or other cleaning products. When released into the air, chlorine will react with water to form acids. When chlorofluorocarbons (CFCs) are emitted and reach the stratosphere, they break apart and release chlorine atoms. Chlorine is very soluble in water and forms a strong acid when dissolved. The chemical symbol for chlorine is Cl. The formula for chlorine gas is Cl₂. 

Chlorine is mainly used to bleach paper and cloth and to make pesticides, chemicals, rubber, and solvents. It is used to kill bacteria in drinking water and swimming pool water. It is also used in the sanitation process for industrial waste and sewage, and as a disinfectant and fungicide. Chlorine, chlorine-based cleaners, and pool chlorination chemicals are made with perchlorate. Polyvinyl chloride (PVC) contains high levels of chlorine.

Most people are generally not exposed to pure chlorine. You may be exposed to non-toxic concentrations of chlorine through household products that are made from chlorine, such as disinfectants used in drinking water and swimming pools. Household bleach does not contain pure chlorine. It is made from sodium hypochlorite, a chlorine-based chemical. However, you can be exposed to hazardous chlorine gas at home if you mix bleach containing sodium hypochlorite with ammonia or other cleaning products. 

You can be exposed to pure chlorine in the air, water, or land in your community if there has been a chlorine spill because of an accident involving a truck or railroad car shipping pure chlorine. You can also be exposed if chlorine has been released by industrial facilities into the air, water, or land. 

Exposure to pure chlorine occurs primarily in industrial situations where chlorine is used. You can be exposed to chlorine at work if you use it for manufacturing other chemicals, bleaches, or disinfectants.

Exposure to extremely high levels of pure chlorine gas can cause lung collapse and death. Exposure to high levels can cause pulmonary edema, rapid breathing, wheezing, blue coloring of the skin, vomiting, anxiety, accumulation of fluid in the lungs, severe eye and skin burns, loss of vision, and lung pain. 

Exposure to low levels of pure chlorine gas is irritating to the respiratory tract, eyes, and skin. Exposure can cause sore or swollen throat, coughing, choking, sneezing, pneumonia, chest tightness and pain, headache, dizziness, watery eyes, blurred vision, nausea, vomiting, vomiting blood, severe abdominal pain, skin blisters and irritation, difficulty breathing, and pain or burning in the stomach, nose, eyes, ears, lips, or tongue. 

If your skin touches pure liquid chlorine, you can get frostbite. 

Some people may develop an inflammatory reaction to chlorine called reactive airways dysfunction syndrome, a type of asthma. 

If you think you have been exposed to pure chlorine or chlorine gas, contact your health care professional. 

For poisoning emergencies or questions about possible poisons, please contact your local poison control center at 1-800-222-1222.

This description is based on the information found in the Web links listed with this topic.

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Last Updated: February 12, 2013