Nitrogen makes up more than 75% of the atmosphere. It is a colorless, odorless, tasteless, nontoxic, almost totally inert gas, and it is colorless as a liquid. Nitrogen is nonflammable, will not support combustion, and is not life supporting. It combines with some of the more active metals such as lithium and magnesium to form nitrides, and at high temperatures it will also combine with hydrogen, oxygen, and other elements.

Liquid nitrogen is extremely cold (–320 °F / –196 °C) and can quickly burn or freeze body tissue. It rapidly turns into a gas and expands rapidly at room temperature. For example, one cubic foot of liquid can expand into 700 cubic feet of gas.

For basic safety information on the handling of compressed gas containers, refer to CGA P-1, Safe Handling of Compressed Gases in Containers. In addition, all of the precautions necessary for the handling of any nonflammable gas or cryogenic liquid must be taken; see your liquid nitrogen supplier’s safety data sheets and CGA P-9, The Inert Gases, Argon, Nitrogen, and Helium. Nitrogen can act as a simple asphyxiant by diluting the concentration of oxygen in air below levels necessary to support life; see CGA P-76, Oxygen‑Deficient Atmospheres, for safety recommendations.

Liquid and gaseous systems should be designed and installed only under the direction of personnel thoroughly familiar with liquid and gaseous nitrogen equipment, and in compliance with state, territorial, provincial, and local requirements.

Disposal of gaseous or liquid nitrogen should only be done by trained, competent personnel. This must be carried out in a responsible manner to ensure that no hazardous conditions are created, all regulatory requirements are met and there is no risk of damage to the environment. See CGA P-63, Disposal of Gases, for additional information.

In the case of a nitrogen leak or liquid nitrogen spill:

• ventilate adjacent enclosed areas to prevent the formation of oxygen-deficient atmospheres;
• evacuate the area;
• DO NOT enter areas where the oxygen concentration is below 19.5% unless provided with a self-contained breathing apparatus (SCBA) or air-line respirator; and
• call your liquid nitrogen supplier immediately for assistance.
• Avoid contact of the skin with liquid nitrogen or its cold boil-off gas. Flush liquid nitrogen spills with water to accelerate evaporation.

Inhalation. Nitrogen is generally inert and can cause asphyxiation due to displacement of oxygen in the atmosphere. Rescuers wearing an SCBA or air-line respirators should move the affected person from the hazardous exposure to fresh air at once. If supplemental oxygen is available, administer by nasal cannula or mask. Perform artificial respiration if the person is not breathing. Persons who have been unconscious should be taken to a hospital for evaluation and care.

Skin contact. In case of frostbite from exposure to liquid nitrogen, the frostbitten part should be placed in warm water, 100 °F to 105 °F (37.8 °C to 40.6 °C). If warm water is not available, or it is impractical to use, wrap the affected part gently in blankets. Let circulation re-establish itself naturally. Encourage the victim to exercise the affected part while it is being warmed. Consult a physician.

Nitrogen is nontoxic and largely inert. It can act as a simple asphyxiant by diluting the concentration of oxygen in air below levels necessary to support life. Inhalation of nitrogen in excessive concentrations can result in dizziness, nausea, vomiting, loss of consciousness, and death. Death can result from errors in judgment, confusion, or loss of consciousness, which prevents self-rescue. At low oxygen concentrations, unconsciousness and death can occur in seconds without warning.

Gaseous nitrogen must be handled with all the precautions necessary for safety with any nonflammable, nontoxic compressed gas. All precautions necessary for the safe handling of any gas liquefied at very low temperatures must be observed with liquid nitrogen. Extensive tissue damage or burns can result from exposure to liquid nitrogen or cold nitrogen vapors. See CGA P-12, Safe Handling of Cryogenic Liquids, for further information.

Physical constants can be found in the CGA Handbook page for Nitrogen