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So it is important to note that despite its decreased use as a refrigerant, ammonia is still making headlines because of its danger to human health. For example, according to a recent item in the Los Angeles Times, an incident last fall at a California nuclear plant caused an ammonia leak, which lead to evacuation of some workers “as a precautionary measure.” (To see the entire article, click here.)
Although injury from ammonia most commonly is caused by inhalation, ammonia injury also may be due to ingestion or direct contact with eyes or skin.
Due to its temperature (-33°C) liquid ammonia freezes skin tissue on contact. Normally, severe skin damage begins at -4°C and becomes irreversible at -20°C. As with any exposure, the degree of severity and damage is proportional to the length of exposure and ammonia concentration. The same is true when ammonia is inhaled — damage to the respiratory system depends on the length of exposure and concentration. Similarly, the degree of tissue injury is also proportional to the duration and concentration of exposure.
According to statistics in the 2009 Annual Report of the American Association of Poison Control Centers’ National Poison Data System, in the United States there were 2,570 single exposures of ammonia. There were three reported fatalities. Over 90 percent of these exposures were classified as intentional — the majority of those through ingestion and not inhalation, which is usually unintentional.
Some consequences of ammonia inhalation include immediate burning of the nose, throat, and respiratory tract leading to bronchiolar and alveolar edema, airway destruction, and respiratory distress or failure. Inhalation can also cause coughing, nose and throat irritation. On the one hand, ammonia’s odor signals its presence, but on the other hand ammonia also causes olfactory fatigue or adaptation, which reduces a person’s awareness of prolonged exposure.
Exposure to low concentrations of ammonia can result in rapid skin or eye irritation, while exposure to higher concentrations can cause severe injury and burns. Contact with concentrated ammonia solutions, i.e., cleaning solutions, can cause corrosive injury including skin burns, permanent eye damage, or blindness. Contact with liquefied ammonia can also cause frostbite injury.
If ingested, ammonia can cause corrosive damage to the mouth, throat, and stomach, but it may not necessarily result in systemic poisoning.
Similar to other poisons, such as carbon monoxide, exposure can be measured by concentrations in ppm (parts per million) in the air. Here are effects of ammonia at various concentrations.
• 25-50 ppm – Detectable odor; unlikely to experience adverse effects;
• 50-100 ppm – Mild eye, nose, and throat irritation; may develop tolerance in one-two weeks with no adverse effects thereafter;
• 140-400 ppm – Moderate eye irritation; moderate throat irritation;
• 700 ppm – Immediate eye injury;
• 1,000 ppm – Directly caustic to airway;
• 2,500 ppm – Fatality (after half-hour exposure).
It is easy to see that exposure to ammonia is no laughing matter. Even though moderate exposure results in little or slight discomfort, lengthy exposure to higher concentrations can result in serious injury or even death.
Proper precaution is the key to healthy employees and lower medical insurance costs — two winning combinations for a growing business. And keeping your refrigeration service and replacement business out of negative headlines can go a long way to staying in business.
Publication date: 03/26/2012