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Occupational Health & Safety: Ammonia

Ammonia photo.jpgCAS Number: 7664-41-7


Ammonia (otherwise known as hydrogen nitride, trihydrogen nitride, nitrogen trihydride) is a nitrogen and hydrogen compound. It is colourless gas with a strong, pungent odour. Compressed it turns to a clear liquid. Ammonia, which is a naturally occurring gas, has a variety of applications in consumer and industrial uses. Industrial ammonia is often sold as pressurized or refrigerated anhydrous liquid ammonia whereas NH3 in water (ammonia hydroxide) is the common household ammonia.

Density: 0.589 times lighter than air.


Worldwide, most ammonia used is in fertilizers. Derived from ammonia, nitric acid is used in the production of fertilizers. Ammonia can be used as a household and industrial cleaning agent, an antimicrobial in food production, in the food fermentation process, as a refrigerant, in explosives, to scrub SO2 when burning fossil fuels, as an ionizing solvent, in pharmaceuticals, in water purification or wastewater treatment and more.

In recent years, more and more wastewater organizations began to measure volatile organic vapours (VOC) in ppm concentrations and in the past year Ammonia in ppm. In a previous blog, we discuss the challenges faced when calibrating these 6 gas detectors.


Global Hazard Statements:  H221 Flammable gas, H280 Contains gas under pressure; may explode if heated, H314 Causes severe skin burns and eye damage, H331 Toxic if inhaled, H400 Very toxic to aquatic life.

Classified as Dangerous Goods by the criteria of the Australian Dangerous Goods Code (ADG Code) for Transport by Road and Rail; DANGEROUS GOODS. This material is hazardous according to Safe Work Australia; HAZARDOUS CHEMICAL.

Flammability Limits: 15.5% – 25. Ammonia is not considered a highly flammable gas. It requires a catalyst and high temperatures to created a potential hazard. In confined spaces in the presence of chlorine, ammonia can become highly explosive.

Liquified ammonia is highly corrosive to the skin and will cause frostbite and injury to skin and eyes. It can cause severe burns to skin and permanent damage to the eyes.

Inhalation can cause nose, throat or lung irritation or difficulty breathing. At high levels may lead to chest pain, bronchial damage pulmonary oedema or death. Acute exposure may increase the future risk of bronchitis or pneumonia.

Occupational Health & Safety Standards

8 hr TWA 17 mg/m3 (25 ppm)
15 min STEL 24 mg/m3 (35 ppm)
PEAK no data available
Acute toxicity:

Oral LD50 (rat)

350 mg/kg
Acute Toxicity:

Inhalation LC50 (rat)

2000 ppm/4hr
Acute Toxicity:

Inhalation LD50 (rat)

7,338 – 11,590 ppm at 1 hour
PPM Effect on Humans
5 – 25 Minor irritation of the eye and respiratory tract, odour threshold.
25 National exposure standard (ES-TWA).
100 No adverse effect for average worker. Deliberate exposure for long periods not permitted.
400 Immediate nose and throat irritation. No serious effects after 30 minutes to 1 hour.
700 Immediate eye irritation. No serious effect after 30 minutes to 1 hour.
1,700 Convulsive coughing. Severe eye, nose and throat irritation. Could be fatal after 30 minutes.
2,000 – 5,000 Convulsive coughing. Severe eye, nose and throat irritation. Could be fatal after 15 minutes.
5,000 Lowest concentration known to be lethal to humans exposed for 5 minutes via inhalation.
5,000 – 10,000 Respiratory spasm. Rapid Asphyxia.

Exposure Prevention:

GHS Precautionary Statements
P210 Keep away from heat, sparks, open flames, hot surfaces. No smoking.
P260 Do not breathe dust / fume / gas / mist / vapours / spray.
P264 Wash hands thoroughly after handling.
P271 Use only outdoors or in a well-ventilated area.
P273 Avoid release to the environment.
P280 Wear protective gloves / protective clothing / eye protection / face protection.

For respiratory protection above 250 ppm, it is recommended to wear a respirator with a full face mask meeting the current standards/requirements. Wear full coverage (long sleeves, pants, gloves, goggles) to protect skin and eyes.


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