Immediately Dangerous to Life or Health (IDLH) for ammonia is 300 parts per million (ppm):

 The NIOSH Immediately Dangerous to Life or Health (IDLH) for ammonia is 300 parts per million (ppm): 

NIOSH

ACGIH

IDLH

300 ppm

—

TWA (10-hour)

25 ppm (18 mg/m3)

25 ppm

STEL (15-minute)

35 ppm (27 mg/m3)

35 ppm

If you might be exposed to more than 300 ppm of ammonia, you should use a NIOSH-approved self-contained breathing apparatus (SCBA) with a full facepiece. You should also consider wearing a chemical protective suit. 

Ammonia is a severe irritant to the eyes, respiratory tract, gastrointestinal tract, and skin. Symptoms include: 

Rapid eye irritation and burning

Nausea, vomiting, and abdominal pain

Burns of the mouth, throat, esophagus, and stomach

Irritation and burns of the nose, trachea, and lungs

Shortness of breath and chest pain

Severe corrosive eye injury, eye redness and swelling, tearing, and temporary or permanent blindness