Will Ammonium Nitrate explode by itself or is there an external agent or catalyst or additive required?

An in-depth look at ammonium nitrate safety and the chemistry behind AN explosions, including real-world triggers and contamination risks

Team PGurus

November 15, 2025

The truth about ammonium nitrate explosions: Myths vs science

An in-depth look at this compound and its properties…

Ammonium Nitrate is a key ingredient in making fertilizers. It is also used as an explosive material.

Ammonium Nitrate (AN) is a chemical compound with the formula NH₄NO₃. While it is a key ingredient in many fertilizers due to its high nitrogen content, it is also known for its explosive properties under certain conditions.

Here’s an impactful infographic explaining whether Ammonium Nitrate explodes by itself:

A detailed scientific explainer on the conditions that make ammonium nitrate explosive, covering heat exposure, contaminants, confinement and decomposition

As the infographic illustrates, pure Ammonium Nitrate does not explode by itself under normal storage conditions. It is quite stable and requires specific conditions and external agents to detonate.

Here’s a detailed breakdown of what is generally required for an Ammonium Nitrate explosion:

Confinement: For an explosion to occur, Ammonium Nitrate usually needs to be confined. This confinement allows pressure to build up, which is crucial for the transition from a deflagration (rapid burning) to a detonation (a supersonic combustion wave). Large stockpiles, silos, or containers can provide this confinement.
High Heat / Initiator: A significant external heat source or an initiating explosive is typically required to start the decomposition reaction.

High Heat: Fires involving combustible materials (like wood pallets, paper, or fuel) near or within a bulk quantity of AN can provide the necessary heat. If heated sufficiently, AN will decompose, releasing gases and further heat. If this process accelerates under confinement, it can lead to an explosion.
Initiator/Detonator: A primary explosive (like dynamite or other high explosives) is often used to initiate a detonation in explosive-grade Ammonium Nitrate mixtures. This provides the shock wave needed to trigger a rapid and violent decomposition.

3. Fuel/Contaminants: While pure Ammonium Nitrate can decompose explosively under extreme conditions of heat and confinement, its explosive potential is significantly enhanced when contaminated or mixed with combustible materials (fuels).

Organic Materials: Substances like oil, grease, paper, wood, carbonaceous materials, or even certain organic fertilizers can act as fuel. These contaminants create a more sensitive and powerful explosive mixture. The infamous Beirut explosion in 2020 involved AN stored near combustible materials.
Other Sensitizers: Certain other chemicals can also sensitize AN, making it more prone to detonation.

In summary: Ammonium Nitrate is relatively safe to handle in its pure, fertilizer-grade form under normal storage conditions. However, it becomes a dangerous explosive hazard when:

It is in large, confined quantities.
Exposed to intense heat (like a large fire).
Mixed with combustible materials or other sensitizers.
Initiated by a primary explosive.

References Used (for the infographic and this explanation):

NFPA 400: Hazardous Materials Code. This code provides comprehensive guidance on the storage and handling of hazardous materials, including ammonium nitrate.
U.S. Geological Survey (USGS) – Ammonium Nitrate Hazards. The USGS provides information on the properties and hazards of ammonium nitrate, particularly in relation to its use in mining and potential for accidents.
Centers for Disease Control and Prevention (CDC) / Agency for Toxic Substances and Disease Registry (ATSDR) – Ammonium Nitrate Toxicity. While primarily focused on toxicity, these sources often include information on chemical properties and hazards.
Various Chemical Safety Databases and Material Safety Data Sheets (MSDS/SDS) for Ammonium Nitrate. These databases (e.g., PubChem, ChemIDplus, specific manufacturer SDS) provide detailed technical information on chemical properties, hazards, and safety precautions.
Academic and Research Papers on Explosives and Chemical Safety. Studies on the decomposition kinetics and explosive properties of ammonium nitrate.
Historical Accident Reports (e.g., Texas City Disaster, Beirut Explosion, Tianjin Explosions). Analysis of these incidents provides critical insights into the real-world conditions leading to ammonium nitrate explosions.

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