Asphyxiation - death of persons

Today, in a lecture, I heard about asphyxiation deaths, in which two persons died in a manufacturing facility. The reason was that instead of air, nitrogen gas was admitted in the work space in which they were working. This happened due to lack of colour coding on pipelines carrying air and nitrogen. Effect of different oxygen levels on human beings is listed below.

     
     % of O2     Effect
20 – 21            Normal
12 – 15            Muscular coordination for skilled movement is lost
10 – 14            Conscious, but judgment is faulty and muscular effort leads to fatigue
  6 – 8              Collapse occurs rapidly, but quick treatment prevents fatal outcome
       ≤ 6            Death occurs in 6 – 8 minutes
   > 60             Inhalation for several days may cause lung damage
35 – 40            Permanent visual impairment / blindness

·         A common symptom at low levels of exposure is headache. 

·         Depletion of O2 by combustion in a confined space may cause adverse health effects Some metals burn intensely in oxygen rich atmosphere (ex: iron wires)

·         Lubricating oil undergoes exothermic reaction causing intense burning in the presence of liquid oxygen

People question the need for measuring oxygen levels with the routine reply that they worked like that in the last 10 years.The main reason for the accidents is not the lack of the knowledge in our work place activities. It is the lack of application of the knowledge we already have.

An activity is being done in a particular fashion without any accident for a few years does not mean that it is safe. We have to remember the words of renowned safety professional, Trevor Kletz, “We have done this way a 100 times without an accident is not acceptable, unless, an accident on the 101^st occasion is acceptable to all of us”.