Residents were forced to evacuate Montague Gardens, Cape Town, on Monday over what was believed to be a chemical spill.
Emergency services responded to what is believed to be a nitric acid spill. Authorities evacuated people and closed roads, warning residents to avoid the area and stay indoors with windows closed due to the toxic fumes.
What is Nitric Acid, and what happens when you inhale the fumes?
Nitric acid (HNO₃) is a strong corrosive acid and oxidiser used in manufacturing fertilisers, metals, and laboratory processes. It can release toxic nitrogen oxide fumes when spilled, especially if heated or mixed with other chemicals.
Breathing in nitric acid vapour or fumes which may include nitrogen dioxid,e can be dangerous:
There are several immediate symptoms to look out for:
- Irritation of eyes, nose, throat and lungs (burning, watery eyes, sore throat)
- Coughing, choking or wheezing
- Chest tightness and shortness of breath
- Headache and dizziness
It is worth noting that these effects may occur even at relatively low exposures.
More serious or delayed effects include:
- Pulmonary oedema (fluid buildup in lungs) may develop hours or even days after exposure
- Severe breathing difficulty
- Possible fatal respiratory distress with high exposures. This delayed lung injury is a major hazard with nitric acid inhalation.
What happens if nitric acid comes into contact with skin or eyes?
When coming into contact with skin, there might be severe chemical burns and deep tissue damage. Burns may not hurt immediately, but they can worsen over time.
Yellow staining of the skin is also common with nitric acid burns. These burns can lead to permanent scarring.
When coming into contact with the eyes, severe eye irritation and burns may occur.
Corneal damage and permanent vision loss or blindness are possible with direct contact.
Other routes of exposure, such as ingestion is less likely but still dangerous.
Ingestion of nitric acid causes severe burns to the mouth, throat, and stomach, and can be life-threatening.
There is no antidote at this point in time, and treatment is supportive and based on symptoms and severity. Pulmonary oedema can be delayed — hours after exposure — and still be severe.
Why are the acid spills treated as high-risk hazmat events?
Nitric acid is highly corrosive and reactive. It releases toxic fumes that are dangerous to breathe. Contact can cause severe burns and permanent injury. In fires or spills, it can react with other materials unpredictably. This is why authorities evacuate and cordon off large areas during such incidents, as seen with the Montague Gardens spill.
The city’s disaster risk management spokesperson Charlotte Powell said the incident was linked to operations at an industrial site.
“Fire and rescue teams are working with the company [the industrial site where it emitted from] to make the building safe and stop the plume from spreading,” she said.
“Evacuations included the premises and areas up to 200 metres downwind.
“Metro rescue, traffic services, and the police are also on site to help.”
