Nitric Acid (HNO3)
Quick Reference
What is HNO3?
Strong acid primarily used in fertilizer and explosive production. It is yellow to reddish-brown in appearance and produces nitrogen dioxide (NO2) fumes that are orange colored. Low water solubility means initial exposure is less immediately irritating to upper airways, potentially prolonging exposure and allowing infiltration to lower airways. Exothermic reaction when mixed with water.
Crew Safety
- Staging/Perimeter
- Isolated spill: 50 m. Crew to stay uphill/upwind. Farther if orange cloud is visible.
- Large tank/transport vessel with fire: 800 m
- Additional Resources
- Industrial emergency response team and/or Fire department HAZMAT team required for rescue.
- PPE requirements
- SCBA and chemical protective clothing required for rescue.
- Safely initiating patient contact
- Patient should be decontaminated and brought to the crew in a safe location.
- Small exposure: crew may meet patient in clean air and direct decontamination from a safe distance.
Effect on the Patient
Contact causes coagulation necrosis. Causes severe eye damage with high risk of permanent blindness as well as severe skin damage. Upper airway irritation with edema may occur, but lower water solubility allows NO2 fumes to travel into lower airways where it is converted back into HNO3. This may cause severe non-cardiogenic pulmonary edema. Onset may be delayed up to 48 hours. Ingestion causes severe GI burns with risk of perforation. Systemic absorption causes methemoglobinemia.
Patient Decontamination
- Remove clothing, do not pull over head. Do not transport clothes with patient.
- Flush exposed eyes with large volumes of water until testing with pH strip confirms pH neutral. Continuous flushing until after handover at the hospital. EYES TAKE PRECEDENCE.
- If skin is exposed, minimum of 30 minutes of flushing with large volume, low pressure water.
Patient Treatment
- EYES TAKE PRECEDENCE, flush eyes continuously until confirmed to be neutral with pH test strip.
- Flush exposed skin with water for 30 minutes.
- Transport to the hospital for possible delayed onset of pulmonary edema.
Safe Transfer of Care
Provided the patient has been decontaminated there is no risk of secondary exposure.
Paramedic and Equipment Decontamination
Provided patient was decontaminated prior to transport no concern present. If patient had residual contamination during transport ventilate ambulance for a minimum of 20 minutes and crew to be assessed for possible exposure to NO2.
Quick Access Resources
DPIC Monograph
No DPIC monograph available.
Paramedic Specialist Safety Data Sheet
Emergency Response Guidebook
Revision History
| Version | Date | Changes | Author |
|---|---|---|---|
| 1.0 | 2026-05-01 | Initial version | Clinical Hub |