What are the limits for exposure to concentrated ammonia?

The ACGIH has determined that the Threshold Limit Value (TLV) for concentrated ammonia for short term exposure is 35 ppm while the time weighted average is 25 ppm. Both of these are defined to ensure the avoidance of irritation to the eyes, nose, and throat. It’s good to remember that TLV’s are not enforced by law, they are merely recommendations to ensure the safety of workers.

Guidance for Exposure Limits

Other exposure limits are made by individual states, their guidelines depend on the scenario of exposure, emergency, or public health assessment. The defined exposure to injury correlation goes as follows:

  • Irritation can occur at as low as 50 ppm for those who are highly sensitive, irritating the eyes, nose, and throat.
  • 100 ppm is the limit for those who are not wearing proper PPE and exposed for about an hour, there are usually no adverse health effects.
  • OSHA determined that 300 ppm is the point at which the side effects can be reversed with time.
  • Without PPE, the maximum an individual can be exposed is 30 minutes at 500 ppm without developing life-threatening effects.
  • Breathing 700-1,700 ppm causes coughing, chest pain, bronchospasm, and severe eye irritation.
  • Anything above 5,000 ppm causes chemical bronchitis, chemical burns of the skin, fluid accumulation, and can be fatal.
  • Permanent lung damage is not necessarily caused by acute exposure, but rather levels that are nearing lethal.

As one can see here, the risks associated with not wearing the proper PPE for handling ammonia are high enough to where it may not be worth putting one’s health in danger by forgoing safety equipment. Not only is it uncomfortable, but the higher ppm concentrations can affect one’s health to the point of inability to heal or even fatality. While this level of extremity doesn’t occur at the lower ppm levels, risk is more associated with the length of time that one is exposed to gaseous ammonia.


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