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Gases - Dangerous Concentration Levels

Dangerous vs. tolerable concentration levels for some industrial gases.

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GasGas Concentration (0/00)
Tolerable > 1 hourTolerable < 1 hourImmediately Dangerous
Ammonia 0.1 0.3 3.5
Bromine Vapor 0.001 0.004 0.05
Carbon Dioxide 10 30 40
Carbon Monoxide 0.2 0.5 2.0
Chlorine Vapor 0.001 0.004 0.05
Hydrochloric Acid 0.01 0.05 1.5
Hydrogen Sulphide 0.2 0.6
Iodine Vapor 0.0005 0.003 0.05
Sulphuric Acid 0.05 0.5
  • 1 ppm = 10-6 = 0.0001 o/o = 0.001 o/oo
  • o/oo  = 1000 ppm 
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Related Topics

  • Physiology

    Human physiology, air quality and comfort temperatures, activity and metabolic rates, health effects of carbon monoxide and more.
  • Risk, Reliability and Safety

    Risk, reliability and safety in process control systems.

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