MSHA Issues Ammonia Health Alert

MSHA recently published a health alert about the hazards of ammonia exposure. According to the agency, ammonia is used on mining sites to process chemicals, in refrigeration systems, and as a neutralizing agent. Exposures can result from equipment leaks or malfunctions and the mixing or improper handling of chemicals. 

Although ammonia’s odor can be detected at levels as low as 5 ppm, “smell alone cannot be relied upon for detection and appropriate warning,” MSHA explains. Industrial hygiene sampling is necessary to monitor ammonia levels and exposures. Ventilation and other engineering controls should be used, the agency states. In cases where miners are wearing respirators, the devices should have ammonia-specific filter cartridges. View the hazard alert on MSHA’s website.

Repeated exposure to ammonia can result in long-term respiratory tract irritation, chronic coughing, asthma, lung fibrosis, reactive airways dysfunction syndrome, and eye and skin irritation, according to CDC.

The NIOSH recommended exposure limit for ammonia is 25 ppm as a time-weighted average for up to a 10-hour work shift. The agency also has a short-term exposure limit (STEL) for ammonia of 35 ppm and an immediately dangerous to life or health (IDLH) value of 300 ppm. 

The ACGIH Threshold Limit Value and STEL for ammonia are 25 ppm (eight-hour TWA) and 35 ppm, respectively. OSHA’s permissible exposure limit is 50 ppm (eight-hour TWA). 

AIHA’s Emergency Response Planning Guidelines specify an ERPG-1 value for ammonia of 25 ppm, the maximum concentration below which nearly all individuals could be exposed for up to one hour without experiencing more than mild, transient adverse health effects. The ERPG-2 and ERPG-3 values, which represent maximum concentrations for one-hour exposures without resulting in serious or life-threatening health effects, are 150 ppm and 1,500 ppm, respectively.