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Ammonia - NH3 - Concentration in Air and Health Effects

Ammonia and health symptoms - smell and threat to life.

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Ammonia - NH3 - is a gas commonly used as a refrigerant in cooling systems.

The gas is colorless with very sharp odor. In small concentrations the gas is detectable by smell. In high concentrations the gas is an immediate hazard to life.

Ammonia concentration in air
Health Symptoms
< 25 Detectable by smell. Maximum Permissible Exposure Limit (PEL)1)
30 Uncomfortable, breathing support required. Maximum exposure 15 minutes1)
50 OSHA2) maximum exposure limit
100 Irritated eyes, throat and mucous membranes. Mild eye, nose, and throat irritation, may develop tolerance in 1-2 weeks with no adverse effects.
140 Moderate eye irritation, no long-term effect in exposures of less than 2 hours
400 Moderate throat irritation. Damage of mucous membranes with more than one hour exposure
500 Immediate danger to life limit (IDLH)
1000 Caustic to airway
1700 Fatal after short exposures - less than half an hour
5000 Immediate hazard to life
> 15000 Full body protection required
160000 - 170000 Flammable in air at 50oC

Lower Flammable Limit (LFL) of Ammonia in air is 15-16% by volume.

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