The Hazards of Nitrogen Asphyxiation

          Nitrogen makes up 78% of the air we breath; because of this it is often assumed that nitrogen is not hazardous.
          However, nitrogen is safe to breath only if it is mixed with an appropriate amount of oxygen.
          Additional nitrogen (lower oxygen) cannot be detected by the sense of smell.
          Nitrogen is used commercially as an inerting agent to keep material free of contaminants (including oxygen) that may corrode equipment, present a fire hazard, or be toxic.
          A lower oxygen concentration (e.g., caused by an increased amount of nitrogen) can have a range of effects on the human body and can be fatal if if falls below 10% 
Effects of Oxygen Deficiency on the Human Body
Atmospheric Oxygen
Concentration (%)
Possible Results
20.9
Normal
19.0
Some unnoticeable adverse physiological effects
16.0
Increased pulse and breathing rate, impaired thinking and attention, reduced coordination
14.0
Abnormal fatigue upon exertion, emotional upset, faulty coordination, poor judgment
12.5
Very poor judgment and coordination, impaired respiration that may cause permanent heart damage, nausea, and vomiting
<10
Inability to move, loss of consciousness, convulsions, death

Good Practices for Safe Handling of Nitrogen
Implement warning systems and continuous atmospheric monitoring of enclosures
          Continuously monitor for oxygen-deficient, toxic, or explosive atmospheres.
          Employ warning systems including flashing lights, alarms, and auto-locking entryways.
          Use personnel monitors to indicate low oxygen concentrations.
          Remember that the atmosphere can change over time.
Ensure ventilation with fresh-air in confined and enclosed areas.
          Maintain continuous forced draft ventilation with fresh air before job begins and through completion.
          Ensure that ventilation systems are properly designed, evaluated, and maintained.
          Use warning systems to alert personnel if the system fails.
Implement a system for the safe retrieval and rescue of workers
          Employees in confined spaces should wear equipment to facilitate retrieval, such as a body harness, anklets, or  wristlets, and a lifeline.
          Standby personnel must be present at all times and have constant communication with personnel inside.
          Personnel should not attempt rescue unless they are properly trained and equipped.    
Ensure the uninterrupted flow and integrity of breathing air
          Take steps to ensure that supplied air is not interrupted. Steps include having alternate sources of power for air compressors, inspecting and replacing air hoses, and restricting traffic in areas with supply hoses.
          Carry escape packs.
          Ensure the composition of supplied breathing air is correct.  Continuously monitor the air supply.
Prevent inadvertent mix-up of nitrogen and breathing air
          Ensure that personnel understand the reason for specific unique fittings on cylinders of different compressed gases. Do not fabricate “adapters” to defeat their purpose.
          Ensure that cylinders are clearly labeled.
          Use color coding to identify systems.
Develop and implement training programs for employees and contract personnel, including information on:
          Proper use of ventilation, retrieval, air monitoring, and air supply systems.
          Safe practices for confined space entry and rescue. Precautions to take when working around confined areas.
          Dangers of nitrogen enriched atmosphere and preventing mix-ups between breathing air and nitrogen.
          Implementing good hazard communication.



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