Beirut Port Explosion (2020): Ammonium Nitrate Blast in Lebanon

The Beirut port explosion of 4 August 2020 was one of the largest accidental non-nuclear explosions ever recorded. Shortly after 6 pm local time, a fire at a warehouse in the port of Beirut, Lebanon, set off about 2,750 tonnes of ammonium nitrate that had been stored there unsafely for six years. The blast killed at least 218 people, injured around 7,000 and devastated large parts of the capital. It became a symbol of the negligence and paralysis of Lebanon’s political system.

Background: a dangerous cargo

Ammonium nitrate is a common industrial chemical used as fertiliser and in mining explosives. It is stable in normal conditions but can detonate when heated in large quantities, especially if contaminated. Earlier disasters, such as the Texas City disaster of 1947, in which a ship loaded with ammonium nitrate exploded in a Texas harbour, had shown how dangerous large stockpiles could be. Because of this, most countries require the chemical to be stored in limited quantities, away from heat sources and from other combustible materials, and well away from homes.

In November 2013 the Moldovan-flagged cargo ship Rhosus, carrying 2,750 tonnes of ammonium nitrate from Georgia to Mozambique, entered Beirut to take on extra cargo. Port authorities detained it over unpaid fees and technical faults, and its owner abandoned it. In 2014 the chemical was unloaded and moved into Hangar 12, a warehouse on the port’s waterfront. Over the following years customs officials, security services and judges sent repeated letters warning of the danger and asking for the material to be removed, sold or re-exported. Nothing was done.

Lebanon in crisis

By 2020 Lebanon was in deep trouble. A financial collapse that began in 2019 had destroyed the value of the currency and savings. Mass protests from October 2019 had brought down one government, and a new cabinet under Prime Minister Hassan Diab had taken office in January 2020. The COVID-19 pandemic added further strain. The political system, built on a power-sharing arrangement between religious communities that dated back to the end of the Lebanese Civil War, was widely seen as corrupt and unaccountable.

The explosion of 4 August 2020

In the late afternoon of 4 August 2020, a fire broke out in Hangar 12, where workers had earlier been carrying out repairs. Firefighters were sent to the scene. Fireworks or other materials stored nearby appear to have caught fire, producing smaller explosions and flashes that many people filmed from across the city.

At about 6:08 pm the ammonium nitrate detonated. A huge mushroom-shaped cloud rose above the port, and a shock wave tore outwards across the city. It flattened warehouses, blew out windows kilometres away and damaged buildings in densely populated neighbourhoods such as Gemmayzeh, Mar Mikhael and Karantina. The blast left a water-filled crater roughly 120 to 140 metres across and was felt and heard in Cyprus, around 240 kilometres away.

Among the dead were ten firefighters and paramedics who had been sent to tackle the original fire. Hospitals, some of them badly damaged themselves, were overwhelmed with injured people. Huge grain silos beside the blast site absorbed part of the shock wave and are thought to have shielded western parts of the city from even worse damage.

How big was the blast?

Scientists used videos, seismic records and the damage pattern to estimate the size of the explosion. Most studies put its force at roughly 0.5 to 1.1 kilotonnes of TNT equivalent, a small fraction of the atomic bomb dropped on Hiroshima but far larger than conventional military bombs. Seismographs recorded it as a tremor of about magnitude 3.3.

Not all of the stored chemical seems to have exploded. An FBI assessment, reported by the news agency Reuters in 2021, estimated that about 550 tonnes detonated, far less than the 2,750 tonnes originally unloaded. This raised further questions, never fully answered, about whether some of the cargo had been removed from the warehouse over the years, or whether part of it simply burned or scattered.

Damage and humanitarian impact

A World Bank assessment estimated physical damage at 3.8 to 4.6 billion US dollars, with economic losses of a further 2.9 to 3.5 billion dollars. Around 300,000 people were left temporarily homeless. Historic buildings from the Ottoman and French Mandate periods, museums and churches were badly damaged. Several major hospitals were put out of action, and more than 150 schools were damaged, at a time when the health system was already struggling with the pandemic.

The destruction of the port, Lebanon’s main gateway for imports, raised fears of food shortages, as much of the country’s grain had been stored in the silos. Aid arrived from many countries. French President Emmanuel Macron visited Beirut on 6 August, and an international donor conference on 9 August pledged around 250 million euros in emergency aid, to be delivered directly to the population rather than through the government.

By the numbers

Political aftermath

Anger at the government was intense. Protesters clashed with security forces in central Beirut and stormed government ministries. On 10 August 2020 Prime Minister Hassan Diab announced the resignation of his government, although it stayed on in a caretaker role for over a year while politicians struggled to form a new one.

Judge Fadi Sawan was appointed to lead the investigation and charged Diab and three former ministers with negligence in December 2020. In February 2021 a court removed Sawan after two of the former ministers challenged him. His successor, Judge Tarek Bitar, sought to question senior politicians and security officials, but his work was halted for long periods by dozens of legal complaints. In October 2021 a protest against him led to deadly armed clashes in Beirut. Bitar resumed the investigation in 2025, but by then no one had been brought to trial.

Legacy

Parts of the damaged grain silos collapsed in July and August 2022 after fires broke out in the rotting grain inside. Families of the victims have campaigned for the remaining structure to be preserved as a memorial, and every 4 August they mark the anniversary with marches demanding justice.

The explosion prompted authorities in many countries to check ports and warehouses for similar stockpiles of hazardous chemicals. In Lebanon it deepened distrust between citizens and the state, and the economic crisis continued for years afterwards.

Timeline

• 2013, November: The cargo ship Rhosus, carrying ammonium nitrate, is detained in Beirut.
• 2014, October: The ammonium nitrate is unloaded into Hangar 12 at the port.
• 2014-2020: Officials send repeated warnings about the stored chemical.
• 2020, 4 August, about 6:08 pm: The ammonium nitrate explodes after a fire in the warehouse.
• 2020, 10 August: Prime Minister Hassan Diab announces his government’s resignation.
• 2020, December: Judge Fadi Sawan charges Diab and three former ministers.
• 2021, February: Sawan is removed; Judge Tarek Bitar takes over the investigation.
• 2022, July-August: Parts of the damaged grain silos collapse.

Why it matters

The Beirut explosion showed how ordinary negligence, repeated over years, could lead to a catastrophe on the scale of a military attack. Coming at the height of Lebanon’s economic collapse, it turned public frustration into outrage and remains a test of whether the country’s institutions can deliver accountability.