Can ammonium nitrate explosions be avoided?

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Because of its potential for accidental explosion and its misuse in improvised explosive devices, ammonium nitrate is classified as a highly hazardous explosive material.

by June Nasrallah and Edgar Choueiri -Source: Annahar

In this August 5, 2020 file photo, smoke rises from the scene of an explosion that hit the seaport of Beirut, Lebanon. (AP Photo)

The massive explosion that caused so many deaths and injuries and devastated large swaths of Beirut has put a spotlight on ammonium nitrate, over 2700 tons of which were stored for years in the city’s port. Investigations are ongoing to determine what triggered the explosion of the ammonium nitrate. But there is no doubt that the devastation which rained on the city and its people would not have occurred in the absence of such a large amount of the chemical.

This explosion is only the latest of over 30 ammonium nitrate-linked explosions that have been recorded worldwide since the early 1900s. Some of these explosions occurred in factories that produce ammonium nitrate or in containers used to transport the chemical by land or sea. Several other explosions resulted from improper storage conditions, in some cases triggered by a nearby fire or other catalysts, as seems to have been the case in the Beirut blast. Sadly, this most recent explosion is one of the largest ammonium nitrate explosions ever recorded and its death toll is the highest of any such explosions that occurred in the last 20 years. It dwarfs the explosion that occurred five years ago at the port of Tianjin, China, in which accidental explosion of 800 tons of ammonium nitrate caused 173 deaths, over 790 injuries, and extensive damage to buildings at and near the port. Only two ammonium nitrate accidents have been more deadly: the 1921 explosion at a manufacturing facility in Oppau, Germany, which killed 561 people and injured more than 2000, and the 1947 explosion at the Houston-area port in Texas, which killed nearly 600 people and injured more than 5000.

Because of its potential for accidental explosion and its misuse in improvised explosive devices, ammonium nitrate is classified as a highly hazardous explosive material. As seen in Beirut, the immediate effects of the shockwave created by ammonium nitrate explosions can be devastating. Additionally, these explosions can have long-term effects on respiratory health due to the air pollution caused by the release of toxic fumes produced by ammonium nitrate decomposition and of particulate matter produced by the destruction of buildings. Despite these hazards, and ever since a method for its synthesis was invented in the early years of the 20th century, ammonium nitrate has been produced in the millions of tons annually across the world. The chemical is now used as a relatively cheap high-nitrogen fertilizer in agriculture and as a major ingredient of explosives used for mining, blasting of rock for quarrying, and construction projects.

Pure ammonium nitrate is considered safe but it becomes highly explosive if contaminated with even small amounts of impurities or stored improperly with no ventilation in the vicinity of flammable carbon-rich materials, such as paper, cardboard, sawdust, or even materials like sugar which are not usually thought to be highly flammable. Consequently, strict science-based regulations for the safe storage and handling of this widespread chemical have been put in place in many countries. These regulations require tightly sealed packaging to prevent the chemical from absorbing moisture and other contaminants; forbid storage near explosives, flammable materials, and equipment with an internal combustion engine; and specify the use of a dedicated well-ventilated storage building constructed from non-combustible materials and equipped with humidity and temperature controls, fire-control devices, and safe electric wiring. An example and details of compliance rules adopted in various countries may be found at https://www.osha.gov/laws-regs/standardinterpretations/2014-12-03.

 

Now that the initial shock of the disastrous August 4 explosion has passed and while we continue to mourn, other similar tragedies must be prevented. Already, the Beirut explosion has caused governments around the world to initiate investigations into the storage of ammonium nitrate at their ports and airports. Similarly, Lebanon should act without delay to identify and secure other stockpiles of ammonium nitrate, no matter how small, which might be stored around the country for agricultural or quarrying operations. The country must adopt and strictly enforce internationally agreed regulations and protocols for the storage, handling, and transport of this chemical, and more generally, of all hazardous materials. This will require a broad distribution of information on the associated hazards, how these hazards should be managed, and what constitutes a proper emergency response. All storage, distribution, and retail facilities should obtain permits that are renewed annually pending inspections to ensure compliance with the regulations. Supervisors and workers in these facilities should be trained appropriately and end-users in agriculture and quarrying operations should be instructed in safe handling practices. Only when these regulations are implemented will it be possible to avoid future catastrophic loss of life, debilitating injuries, and costly damage to property.

June Nasrallah is the current President of the Lebanese Academy of Sciences and Professor at Cornell University and Edgar Choueiri is the founding President of the Lebanese Academy of Sciences and Professor, Princeton University

 

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