Toxicology – Ammonia

Core Concept

Ammonia (NH₃) is a highly water-soluble, alkaline irritant gas with a strong pungent odor.

Important forms include:

• Anhydrous ammonia – concentrated gas or pressurized/liquefied ammonia used industrially
• Aqueous ammonia – ammonia dissolved in water
• Dilute household cleaning products
• More concentrated industrial/commercial solutions

The major toxic effect is direct chemical injury at the site of contact, especially involving:

• Eyes
• Upper airway
• Lungs
• Skin
• Gastrointestinal tract

There is no specific antidote.

Common Sources and Uses

Ammonia is used in:

• Fertilizer production
• Refrigeration systems
• Chemical manufacturing
• Plastics and synthetic fibers
• Pharmaceutical and dye production
• Industrial cleaning
• Household cleaning products

Severe exposures are particularly associated with:

• Industrial spills
• Refrigeration accidents
• Agricultural exposure
• Pressurized anhydrous ammonia
• Concentrated cleaning solutions

Routes of Exposure

Toxicity can occur through:

• Inhalation
• Ocular exposure
• Dermal contact
• Ingestion

Severity depends strongly on:

• Concentration
• Duration
• Route
• Amount
• Enclosed-space exposure
• Delay before decontamination

Mechanism of Injury

Ammonia is extremely soluble in water.

On contact with moist tissues, ammonia produces an alkaline environment traditionally represented as:

NH₃ + H₂O ⇌ NH₄⁺ + OH⁻

The resulting hydroxide-rich environment causes direct chemical injury.

Alkaline injury can produce:

• Protein disruption
• Cell membrane damage
• Inflammation
• Tissue penetration
• Liquefactive-type necrosis in substantial exposures

Why the Eyes and Airways Are Vulnerable

The:

• Tear film
• Nasal mucosa
• Oropharynx
• Respiratory epithelium

contain abundant water.

Ammonia therefore dissolves rapidly at these surfaces, explaining its intense immediate irritant effect.

Anhydrous Ammonia

Anhydrous ammonia is particularly hazardous because it may be stored under pressure as a liquefied gas.

Release can cause:

• Very high local vapor concentrations
• Severe inhalational injury
• Chemical burns
• Eye injury

Contact with liquefied ammonia can also produce cold-related tissue injury from rapid evaporation in addition to chemical injury.

Inhalational Toxicity

Because ammonia is highly water soluble, much of the initial injury occurs in the upper respiratory tract.

Symptoms may include:

• Burning of the nose and throat
• Cough
• Hoarseness
• Chest discomfort
• Dyspnea
• Wheezing
• Tachypnea

More severe exposure can produce:

• Laryngeal edema
• Laryngospasm
• Stridor
• Bronchospasm
• Chemical pneumonitis
• Acute lung injury
• Noncardiogenic pulmonary edema
• Respiratory failure

Airway Injury

Upper-airway injury is one of the most important immediate threats.

Warning findings include:

• Stridor
• Progressive hoarseness
• Drooling
• Dysphagia
• Respiratory distress
• Oropharyngeal burns
• Increasing work of breathing
• Altered mental status

Airway edema can progress after exposure.

Therefore:

A threatened airway should be secured before edema makes airway management substantially more difficult.

Pulmonary Injury

Lower-airway injury may produce:

• Cough
• Wheezing
• Bronchospasm
• Crackles
• Hypoxemia
• Chemical pneumonitis
• Acute lung injury

Pulmonary edema may evolve after a substantial exposure.

An initially reassuring examination or chest radiograph does not completely exclude evolving lung injury.

Reactive Airways Dysfunction

After significant irritant exposure, some patients can develop persistent airway hyperreactivity, sometimes described as reactive airways dysfunction syndrome (RADS).

Persistent symptoms may include:

• Cough
• Wheezing
• Chest tightness
• Exercise intolerance

Significant exposures may therefore require pulmonary follow-up.

Eye Exposure

Ammonia can rapidly cause severe ocular injury.

Possible manifestations include:

• Burning pain
• Lacrimation
• Conjunctival injection
• Blepharospasm
• Corneal epithelial injury
• Corneal burns
• Visual impairment

High-concentration exposure can threaten vision.

Immediate Ocular Management

The priority is:

Immediate copious irrigation

Do not delay irrigation to:

• Identify the exact concentration
• Measure ocular pH
• Perform a detailed examination

After initial irrigation, ocular pH can help determine whether additional irrigation is required.

Persistent:

• Pain
• Photophobia
• Visual disturbance
• Corneal abnormalities

requires urgent ophthalmic evaluation.

Skin Exposure

Dermal exposure may produce:

• Pain
• Erythema
• Irritant dermatitis
• Blistering
• Chemical burns
• Deeper tissue injury after concentrated exposure

Liquefied anhydrous ammonia may additionally cause cold injury.

Dermal Decontamination

Management begins with:

• Removal from the contaminated environment
• Removal of contaminated clothing
• Copious irrigation
• Standard assessment of resulting chemical/cold burns

Significant burns should be managed according to burn-care principles.

Ingestion

Aqueous ammonia ingestion primarily produces corrosive gastrointestinal injury.

Possible symptoms include:

• Oral pain
• Drooling
• Dysphagia
• Odynophagia
• Vomiting
• Chest pain
• Abdominal pain

Severe exposure can injure:

• Oropharynx
• Esophagus
• Stomach

Absence of Oral Burns Does Not Exclude Deeper Injury

A normal-looking mouth does not reliably exclude esophageal or gastric injury after a significant caustic ingestion.

Assessment should therefore consider:

• Product concentration
• Amount
• Intent
• Drooling
• Dysphagia/odynophagia
• Chest or abdominal pain
• Vomiting
• Respiratory findings

GI Complications

Severe corrosive injury may result in:

• Ulceration
• Necrosis
• Perforation
• Mediastinitis or peritonitis
• Later esophageal stricture formation

Long-term swallowing problems may therefore develop after significant injury.

Do Not Induce Vomiting

Vomiting should never be intentionally induced after ammonia ingestion.

Re-exposure of the upper GI tract can worsen injury and increase aspiration risk.

Ipecac has no role.

Do Not Neutralize

Do not attempt to neutralize ammonia with an acid.

Chemical neutralization can:

• Generate heat
• Produce additional tissue damage
• Delay appropriate care

The same general principle applies to caustic ingestions:

Do not attempt home chemical neutralization.

Routine Gastric Lavage Is Contraindicated

Gastric lavage is generally inappropriate after caustic ammonia ingestion because it can:

• Re-expose injured tissue
• Increase perforation risk
• Cause aspiration
• Produce additional mechanical trauma

Activated Charcoal

Activated charcoal is generally not useful for ammonia ingestion.

It does not meaningfully prevent the immediate local corrosive injury and may interfere with subsequent endoscopic evaluation.

Oral Dilution – Modern Perspective

Older references sometimes recommended routine administration of water or milk after caustic ingestion.

Modern management does not rely on routine forced dilution.

Do not give large volumes because this may:

• Trigger vomiting
• Increase gastric distension
• Increase aspiration risk

Immediate advice after ingestion should follow current poison-center or caustic-ingestion guidance.

Ammonia + Bleach

Mixing ammonia-containing cleaners with hypochlorite bleach can generate chloramine gases and related respiratory irritants.

This can cause:

• Eye and throat irritation
• Cough
• Chest tightness
• Bronchospasm
• Dyspnea
• Chemical pneumonitis in substantial exposure

The resulting illness should be managed as an irritant gas inhalation, rather than assuming exposure to ammonia alone.

Reactive Airway Disease

Patients with:

• Asthma
• Other reactive airway disease

may experience more pronounced bronchospasm after ammonia or chloramine exposure.

Diagnosis

Diagnosis is usually based on:

• Exposure history
• Product concentration
• Route
• Duration
• Respiratory examination
• Ocular/skin findings
• GI symptoms after ingestion

There is no clinically useful routine serum “ammonia level” for diagnosing inhalational or caustic ammonia exposure.

A plasma ammonia measurement used in hepatic encephalopathy evaluates an entirely different clinical problem.

Laboratory Evaluation

Minor asymptomatic exposure may require no laboratory testing.

For significant inhalational injury, testing may include:

• Pulse oximetry
• Blood gas when respiratory compromise is present
• Electrolytes and other general tests when clinically indicated

Severe caustic ingestion may require additional laboratory evaluation based on the extent of systemic illness.

Chest Imaging

Chest radiography is appropriate when there are significant respiratory symptoms or suspected pulmonary injury.

Possible findings include:

• Infiltrates
• Pulmonary edema
• Other evidence of acute lung injury

However:

A normal early chest radiograph does not exclude evolving inhalational injury.

Bronchoscopy

Bronchoscopy is not automatically required after every ammonia exposure.

It may be considered after substantial inhalation when clinicians need to evaluate significant airway injury.

Airway stabilization always takes priority over diagnostic bronchoscopy.

Endoscopy After Ingestion

Upper GI endoscopy may be appropriate after clinically significant caustic ingestion, particularly when there are concerning symptoms or a substantial concentrated exposure.

It can help assess:

• Esophageal injury
• Gastric injury
• Severity and prognosis

Timing and need should follow contemporary caustic-ingestion protocols and specialist assessment rather than an automatic rule that every exposure undergo endoscopy.

Initial Management – Inhalation

Priorities are:

• Remove from exposure
• Protect rescuers from contamination
• Assess airway immediately
• Provide oxygen when indicated
• Treat bronchospasm
• Monitor for progressive airway or pulmonary injury

Severe exposure warrants early involvement of airway/critical-care specialists.

Oxygen

Supplemental oxygen is appropriate for:

• Hypoxemia
• Respiratory distress
• Significant inhalational injury

The historical routine recommendation for 100% oxygen after every ammonia exposure is unnecessary in a patient with trivial exposure and normal respiratory status.

Bronchospasm

Clinically significant wheezing or airflow obstruction can be treated with an inhaled β₂-agonist bronchodilator.

Patients with severe bronchospasm require close respiratory monitoring.

Corticosteroids

Routine corticosteroids have not been proven to prevent ammonia-induced pulmonary injury.

They should not automatically be administered after every inhalation.

They may be used when another established indication exists, such as a clinically important asthma exacerbation.

Antibiotics

Prophylactic antibiotics are not routinely indicated for uncomplicated chemical pneumonitis.

They are reserved for suspected or demonstrated infection or another specific indication.

Severe Lung Injury

Progressive respiratory failure is treated with standard supportive respiratory care.

This may include:

• Supplemental oxygen
• Appropriate noninvasive support in selected patients
• Endotracheal intubation when necessary
• Lung-protective mechanical ventilation for severe acute lung injury

There is no ammonia-specific antidotal therapy.

No Specific Antidote

There is no antidote for ammonia poisoning.

Treatment consists of:

Exposure termination + immediate decontamination + airway management + supportive respiratory/GI/burn care

Monitoring

Symptomatic patients may require monitoring of:

• Respiratory rate and effort
• Oxygen saturation
• Airway findings
• Heart rate and blood pressure
• Lung examination
• Mental status

After significant ingestion, monitor for:

• Dysphagia
• Chest/abdominal pain
• GI bleeding
• Perforation
• Subsequent stricture formation

Observation and Disposition

A fixed historical 6-hour rule should not be applied to every exposure.

Observation depends on:

• Concentration
• Route
• Duration
• Symptoms
• Respiratory findings
• Ocular/dermal injury
• Evidence of caustic GI injury
• Clinical trajectory

Patients with significant airway injury, hypoxemia, bronchospasm, pulmonary injury, or substantial caustic ingestion generally require continued hospital management.

Long-Term Complications

After inhalation

Possible persistent complications include:

• Airway hyperreactivity
• Chronic cough
• Obstructive abnormalities
• Other residual pulmonary dysfunction after severe injury

After ingestion

Severe esophageal injury may heal with:

• Fibrosis
• Stricture formation
• Chronic dysphagia

Follow-up is therefore important after substantial caustic injury.

Safeguarding

The older source uses rigid age thresholds for suspected neglect or intentional poisoning.

Modern assessment instead considers:

• Developmental ability
• Accessibility of the chemical
• Circumstances of exposure
• Consistency of the history
• Previous unexplained injuries or poisonings

Age alone does not establish abuse or neglect.

Occupational Exposure

Anhydrous ammonia is an important occupational hazard.

Prevention depends on:

• Engineering controls
• Appropriate respiratory/eye/skin protection
• Safe handling of pressurized systems
• Emergency decontamination capability

Historical numerical exposure limits should be verified against current occupational standards for the relevant jurisdiction.

Important Modernization of the Older Source

• Ammonia is a highly water-soluble alkaline irritant producing direct chemical injury.
• High-concentration inhalation can cause upper-airway edema, bronchospasm, chemical pneumonitis, acute lung injury, and respiratory failure.
• Liquefied anhydrous ammonia can cause both chemical and cold-related tissue injury.
• A normal early chest X-ray does not exclude evolving lung injury.
• Airway edema can progress; a threatened airway should be managed early.
• Immediate copious irrigation is the priority for ocular and dermal exposure.
• Do not delay eye irrigation to measure pH first.
• Significant ingestion is managed according to caustic-ingestion principles.
• Absence of visible oral burns does not exclude deeper esophageal injury.
• Do not induce vomiting.
• Do not attempt acid–base neutralization.
• Routine gastric lavage and activated charcoal are inappropriate.
• Routine forced dilution with large volumes of water or milk is no longer a standard strategy.
• Bronchoscopy and GI endoscopy are used selectively according to severity and specialist assessment.
• Bronchodilators are appropriate for bronchospasm.
• Routine corticosteroids have not been proven to prevent ammonia lung injury.
• There is no specific antidote.
• Mixing ammonia with hypochlorite bleach can generate chloramine-type irritant gases.
• Fixed historical observation periods should be replaced by exposure- and symptom-based assessment.

Key Points

• NH₃ + moist tissue → alkaline environment → direct chemical injury.
• Major targets are the eyes, upper airway, lungs, skin, esophagus, and stomach.
• Concentrated/anhydrous ammonia can rapidly cause airway edema and severe respiratory injury.
• Watch for stridor, hoarseness, drooling, wheezing, hypoxemia, and increasing respiratory distress.
• An initially normal chest radiograph does not rule out evolving lung injury.
• Eye or skin exposure requires immediate copious irrigation.
• Significant ingestion is treated as a caustic alkali exposure.
• Never induce vomiting or attempt chemical neutralization.
• Activated charcoal has no routine role.
• Treat bronchospasm supportively and secure a threatened airway early.
• No specific antidote exists.

Common Sources and Uses Ammonia is used in:  Fertilizer production Refrigeration systems Chemical manufacturing Plastics and synthetic fibers Pharmaceutical and dye production Industrial cleaning Household cleaning products  Severe exposures are particularly associated with:  Industrial spills Refrigeration accidents Agricultural exposure Pressurized anhydrous ammonia Concentrated cleaning solutions

Routes of Exposure Toxicity can occur through:  Inhalation Ocular exposure Dermal contact Ingestion  Severity depends strongly on:  Concentration Duration Route Amount Enclosed-space exposure Delay before decontamination

Mechanism of Injury Ammonia is extremely soluble in water. On contact with moist tissues, ammonia produces an alkaline environment traditionally represented as: NH₃ + H₂O ⇌ NH₄⁺ + OH⁻ The resulting hydroxide-rich environment causes direct chemical injury. Alkaline injury can produce:  Protein disruption Cell membrane damage Inflammation Tissue penetration Liquefactive-type necrosis in substantial exposures

Why the Eyes and Airways Are Vulnerable The:  Tear film Nasal mucosa Oropharynx Respiratory epithelium  contain abundant water. Ammonia therefore dissolves rapidly at these surfaces, explaining its intense immediate irritant effect.

Anhydrous Ammonia Anhydrous ammonia is particularly hazardous because it may be stored under pressure as a liquefied gas. Release can cause:  Very high local vapor concentrations Severe inhalational injury Chemical burns Eye injury  Contact with liquefied ammonia can also produce cold-related tissue injury from rapid evaporation in addition to chemical injury.

Inhalational Toxicity Because ammonia is highly water soluble, much of the initial injury occurs in the upper respiratory tract. Symptoms may include:  Burning of the nose and throat Cough Hoarseness Chest discomfort Dyspnea Wheezing Tachypnea  More severe exposure can produce:  Laryngeal edema Laryngospasm Stridor Bronchospasm Chemical pneumonitis Acute lung injury Noncardiogenic pulmonary edema Respiratory failure

Airway Injury Upper-airway injury is one of the most important immediate threats. Warning findings include:  Stridor Progressive hoarseness Drooling Dysphagia Respiratory distress Oropharyngeal burns Increasing work of breathing Altered mental status  Airway edema can progress after exposure. Therefore: A threatened airway should be secured before edema makes airway management substantially more difficult.

Pulmonary Injury Lower-airway injury may produce:  Cough Wheezing Bronchospasm Crackles Hypoxemia Chemical pneumonitis Acute lung injury  Pulmonary edema may evolve after a substantial exposure. An initially reassuring examination or chest radiograph does not completely exclude evolving lung injury.

Reactive Airways Dysfunction After significant irritant exposure, some patients can develop persistent airway hyperreactivity, sometimes described as reactive airways dysfunction syndrome (RADS). Persistent symptoms may include:  Cough Wheezing Chest tightness Exercise intolerance  Significant exposures may therefore require pulmonary follow-up.

Eye Exposure Ammonia can rapidly cause severe ocular injury. Possible manifestations include:  Burning pain Lacrimation Conjunctival injection Blepharospasm Corneal epithelial injury Corneal burns Visual impairment  High-concentration exposure can threaten vision.

Immediate Ocular Management The priority is: Immediate copious irrigation Do not delay irrigation to:  Identify the exact concentration Measure ocular pH Perform a detailed examination  After initial irrigation, ocular pH can help determine whether additional irrigation is required. Persistent:  Pain Photophobia Visual disturbance Corneal abnormalities  requires urgent ophthalmic evaluation.

Skin Exposure Dermal exposure may produce:  Pain Erythema Irritant dermatitis Blistering Chemical burns Deeper tissue injury after concentrated exposure  Liquefied anhydrous ammonia may additionally cause cold injury.

Dermal Decontamination Management begins with:  Removal from the contaminated environment Removal of contaminated clothing Copious irrigation Standard assessment of resulting chemical/cold burns  Significant burns should be managed according to burn-care principles.

Ingestion Aqueous ammonia ingestion primarily produces corrosive gastrointestinal injury. Possible symptoms include:  Oral pain Drooling Dysphagia Odynophagia Vomiting Chest pain Abdominal pain  Severe exposure can injure:  Oropharynx Esophagus Stomach

Absence of Oral Burns Does Not Exclude Deeper Injury A normal-looking mouth does not reliably exclude esophageal or gastric injury after a significant caustic ingestion. Assessment should therefore consider:  Product concentration Amount Intent Drooling Dysphagia/odynophagia Chest or abdominal pain Vomiting Respiratory findings

GI Complications Severe corrosive injury may result in:  Ulceration Necrosis Perforation Mediastinitis or peritonitis Later esophageal stricture formation  Long-term swallowing problems may therefore develop after significant injury.

Do Not Induce Vomiting Vomiting should never be intentionally induced after ammonia ingestion. Re-exposure of the upper GI tract can worsen injury and increase aspiration risk. Ipecac has no role.

Do Not Neutralize Do not attempt to neutralize ammonia with an acid. Chemical neutralization can:  Generate heat Produce additional tissue damage Delay appropriate care  The same general principle applies to caustic ingestions: Do not attempt home chemical neutralization.

Routine Gastric Lavage Is Contraindicated Gastric lavage is generally inappropriate after caustic ammonia ingestion because it can:  Re-expose injured tissue Increase perforation risk Cause aspiration Produce additional mechanical trauma

Activated Charcoal Activated charcoal is generally not useful for ammonia ingestion. It does not meaningfully prevent the immediate local corrosive injury and may interfere with subsequent endoscopic evaluation.

Oral Dilution – Modern Perspective Older references sometimes recommended routine administration of water or milk after caustic ingestion. Modern management does not rely on routine forced dilution. Do not give large volumes because this may:  Trigger vomiting Increase gastric distension Increase aspiration risk  Immediate advice after ingestion should follow current poison-center or caustic-ingestion guidance.

Ammonia + Bleach Mixing ammonia-containing cleaners with hypochlorite bleach can generate chloramine gases and related respiratory irritants. This can cause:  Eye and throat irritation Cough Chest tightness Bronchospasm Dyspnea Chemical pneumonitis in substantial exposure  The resulting illness should be managed as an irritant gas inhalation, rather than assuming exposure to ammonia alone.

Reactive Airway Disease Patients with:  Asthma Other reactive airway disease  may experience more pronounced bronchospasm after ammonia or chloramine exposure.

Diagnosis Diagnosis is usually based on:  Exposure history Product concentration Route Duration Respiratory examination Ocular/skin findings GI symptoms after ingestion  There is no clinically useful routine serum “ammonia level” for diagnosing inhalational or caustic ammonia exposure. A plasma ammonia measurement used in hepatic encephalopathy evaluates an entirely different clinical problem.

Laboratory Evaluation Minor asymptomatic exposure may require no laboratory testing. For significant inhalational injury, testing may include:  Pulse oximetry Blood gas when respiratory compromise is present Electrolytes and other general tests when clinically indicated  Severe caustic ingestion may require additional laboratory evaluation based on the extent of systemic illness.

Chest Imaging Chest radiography is appropriate when there are significant respiratory symptoms or suspected pulmonary injury. Possible findings include:  Infiltrates Pulmonary edema Other evidence of acute lung injury  However: A normal early chest radiograph does not exclude evolving inhalational injury.

Bronchoscopy Bronchoscopy is not automatically required after every ammonia exposure. It may be considered after substantial inhalation when clinicians need to evaluate significant airway injury. Airway stabilization always takes priority over diagnostic bronchoscopy.

Endoscopy After Ingestion Upper GI endoscopy may be appropriate after clinically significant caustic ingestion, particularly when there are concerning symptoms or a substantial concentrated exposure. It can help assess:  Esophageal injury Gastric injury Severity and prognosis  Timing and need should follow contemporary caustic-ingestion protocols and specialist assessment rather than an automatic rule that every exposure undergo endoscopy.

Initial Management – Inhalation Priorities are:  Remove from exposure Protect rescuers from contamination Assess airway immediately Provide oxygen when indicated Treat bronchospasm Monitor for progressive airway or pulmonary injury  Severe exposure warrants early involvement of airway/critical-care specialists.

Oxygen Supplemental oxygen is appropriate for:  Hypoxemia Respiratory distress Significant inhalational injury  The historical routine recommendation for 100% oxygen after every ammonia exposure is unnecessary in a patient with trivial exposure and normal respiratory status.

Bronchospasm Clinically significant wheezing or airflow obstruction can be treated with an inhaled β₂-agonist bronchodilator. Patients with severe bronchospasm require close respiratory monitoring.

Corticosteroids Routine corticosteroids have not been proven to prevent ammonia-induced pulmonary injury. They should not automatically be administered after every inhalation. They may be used when another established indication exists, such as a clinically important asthma exacerbation.

Antibiotics Prophylactic antibiotics are not routinely indicated for uncomplicated chemical pneumonitis. They are reserved for suspected or demonstrated infection or another specific indication.

Severe Lung Injury Progressive respiratory failure is treated with standard supportive respiratory care. This may include:  Supplemental oxygen Appropriate noninvasive support in selected patients Endotracheal intubation when necessary Lung-protective mechanical ventilation for severe acute lung injury  There is no ammonia-specific antidotal therapy.

No Specific Antidote There is no antidote for ammonia poisoning. Treatment consists of: Exposure termination + immediate decontamination + airway management + supportive respiratory/GI/burn care

Monitoring Symptomatic patients may require monitoring of:  Respiratory rate and effort Oxygen saturation Airway findings Heart rate and blood pressure Lung examination Mental status  After significant ingestion, monitor for:  Dysphagia Chest/abdominal pain GI bleeding Perforation Subsequent stricture formation

Observation and Disposition A fixed historical 6-hour rule should not be applied to every exposure. Observation depends on:  Concentration Route Duration Symptoms Respiratory findings Ocular/dermal injury Evidence of caustic GI injury Clinical trajectory  Patients with significant airway injury, hypoxemia, bronchospasm, pulmonary injury, or substantial caustic ingestion generally require continued hospital management.

Long-Term Complications After inhalation Possible persistent complications include:  Airway hyperreactivity Chronic cough Obstructive abnormalities Other residual pulmonary dysfunction after severe injury  After ingestion Severe esophageal injury may heal with:  Fibrosis Stricture formation Chronic dysphagia  Follow-up is therefore important after substantial caustic injury.

Safeguarding The older source uses rigid age thresholds for suspected neglect or intentional poisoning. Modern assessment instead considers:  Developmental ability Accessibility of the chemical Circumstances of exposure Consistency of the history Previous unexplained injuries or poisonings  Age alone does not establish abuse or neglect.

Occupational Exposure Anhydrous ammonia is an important occupational hazard. Prevention depends on:  Engineering controls Appropriate respiratory/eye/skin protection Safe handling of pressurized systems Emergency decontamination capability  Historical numerical exposure limits should be verified against current occupational standards for the relevant jurisdiction.

Important Modernization of the Older Source  Ammonia is a highly water-soluble alkaline irritant producing direct chemical injury. High-concentration inhalation can cause upper-airway edema, bronchospasm, chemical pneumonitis, acute lung injury, and respiratory failure. Liquefied anhydrous ammonia can cause both chemical and cold-related tissue injury. A normal early chest X-ray does not exclude evolving lung injury. Airway edema can progress; a threatened airway should be managed early. Immediate copious irrigation is the priority for ocular and dermal exposure. Do not delay eye irrigation to measure pH first. Significant ingestion is managed according to caustic-ingestion principles. Absence of visible oral burns does not exclude deeper esophageal injury. Do not induce vomiting. Do not attempt acid–base neutralization. Routine gastric lavage and activated charcoal are inappropriate. Routine forced dilution with large volumes of water or milk is no longer a standard strategy. Bronchoscopy and GI endoscopy are used selectively according to severity and specialist assessment. Bronchodilators are appropriate for bronchospasm. Routine corticosteroids have not been proven to prevent ammonia lung injury. There is no specific antidote. Mixing ammonia with hypochlorite bleach can generate chloramine-type irritant gases. Fixed historical observation periods should be replaced by exposure- and symptom-based assessment.  Key Points  NH₃ + moist tissue → alkaline environment → direct chemical injury. Major targets are the eyes, upper airway, lungs, skin, esophagus, and stomach. Concentrated/anhydrous ammonia can rapidly cause airway edema and severe respiratory injury. Watch for stridor, hoarseness, drooling, wheezing, hypoxemia, and increasing respiratory distress. An initially normal chest radiograph does not rule out evolving lung injury. Eye or skin exposure requires immediate copious irrigation. Significant ingestion is treated as a caustic alkali exposure. Never induce vomiting or attempt chemical neutralization. Activated charcoal has no routine role. Treat bronchospasm supportively and secure a threatened airway early. No specific antidote exists.