ELi5: What makes white phosphorus so dangerous when used as a weapon of war?


ELi5: What makes white phosphorus so dangerous when used as a weapon of war?

In: 291

It ignites with the air, it doesn’t need any spark or ignition source.

It’s also sticky so once it gets on something there’s no getting it off until it burns itself off.

It’s also very toxic.

It’s pretty much just death.

WP can reach 5000 degrees F, meaning it’ll burn straight through flesh and bone. Additionally, you adsorb the Phosphorous in toxic amounts, which can lead to massive organ failure.

Its just really nasty stuff. It burns incredibly hot. Like burns you straight down to the bone level hot. It will ignite when it comes in contact with air so its very difficult to actually put out. If you manage to actually put the stuff out it will just re-ignite the second it comes in contact with air. its also toxic to come in prolonged contact with.

Its basically creates sticky, self igniting, toxic fire, that can burn you to the bone.

As others have explained, getting white phosphorus on your body is incredibly damaging. But what has not been mentioned is how it is “applied” to people: usually chunks of it are exploded in a way that makes it quite indiscriminate. For instance, in 2008-2009 Israel used white phosphorus shells allegedly to provide smoke screens. When these shells explode “the canister deploys 116 units 19 millimetres (0.75 in), quarter-circle wedges of felt impregnated with 5.8 kilograms (12.75 lb) of WP, producing a smokescreen lasting 5–10 minutes depending on weather conditions. These submunitions typically land in an elliptical pattern 125–250 meters in diameter” (Wikipedia, White phosphorus munitions). An area that large in an urban area is not targeting anyone specific, or even a small group of people or a specific installation – it is almost guaranteed to indiscriminately severely injure many people.

You can’t put it out conventionally. It ignites when exposed to air, so water, suffocation and fire extinguishers can’t really stop it. It’s a nasty thing.

“Dangerous” may not be the right term.

White phosphorus is a white, wax-like substance. It self-ignites very easily, and burns extremely hot and fast – 2760°C/5000°F. That is enough to destroy most types of clothing and armour, get down to skin, and cause fourth-degree burns in seconds. Since it’s a waxy solid, it sticks to you as it’s burning you, making it hard to escape from. Imagine being splattered with hot candle wax that burns through your clothes, skin and muscles, where it sticks to your bones.

Because of its nature, before such wounds can be treated, physicians must ensure all traces of phosphorus are removed. Multiple stories exist of white phosphorus victims who have been weeks into recovery, when a bandage has been removed, exposing some small trace of leftover phosphorus to oxygen and igniting it again.

It’s also extremely toxic. Breathing in white phosphorus fumes can seriously irritate your lungs and eventually cause a condition called phossy jaw, which involves your lower jaw breaking down. Ingesting it causes liver damage and eventual liver failure.

It’s no more “dangerous” than being shot in the head or dismembered. However, it is widely considered an extremely immoral, inhumane weapon for two reasons:

1) it is usually deployed through the use of grenades, missiles, or other explosives. This causes *indiscriminate* sprays of white phosphorus, which may hit unintended targets, and often does.

2) It is an extremely painful, agonising way to go, and extremely traumatising to watch. While most white phosphorus victims die, those who survive are often permanently disfigured.

The simplest answer is that white phosphorous, in the presence of oxygen, continues to burn and consume whatever it comes in contact with. For a human being, it is particularly agonizing.

Well, it burns at 5000 degrees, is pyrophoric (self-igniting), basically impossible to extinguish, and produces highly toxic (and opaque) smoke that turns into phosphoric acid.

It reacts with water. Your body is pretty much a bag of water. Phosphorus will keep reacting with any source of water. Such as your body. It will keep burning until the supply of water is gone. Horrific.

A game called Spec Ops: the line has a mass murder scene using white phosphorus. It’s been years and still haunt me.

it’s often indiscriminate and causes much much more suffering than is needed to make a person stop fighting.

In addition to the other good answers here, WP can survive (not burn) if it’s covered with dirt. As a Canadian infantryman, mid 1980s, I personally kicked over a clump of dirt and *poof*, a small bit of WP started on fire. Could be dangerous if combustibles nearby (grass, leaves, etc.). We knew to expect it. Didn’t happen often.


In confined spaces, it burns out the oxygen and kills victims by asphyxiation. On flesh, it produces horrific burns and flames that are very hard to put out.

Ignites from air, burns super hot, literally can’t put it out. Jump in water and it’ll just split the water atoms into hydrogen/oxygen and make them burn too.

Its pretty fucking horrific.

Something I didn’t really see mentioned was the reasoning for *why* it’s still used officially.

Weight-for-weight, Willie Pete is the most effective smoke screening agent yet discovered. The vapor that comes off burning WP is phosphorus pentoxide, but on contact with the water in the air that immediately turns to phosphoric acid droplets. This means that whatever mass of vapor you produce is going to be tripled in mass by the water in the air, giving you insane amounts of smoke.
P4O10 + 6 H2O → 4 H3PO4.

Also, this means WP smoke isn’t actually smoke at all, it’s an aerosol. This means it actually scatters light instead of just providing a screen, which makes it much more effective at blocking view. Basically, it works like privacy glass instead of a cloud of smoke. Importantly, it absorbs infrared, meaning it can be used to hide from thermal imaging cameras.

So officially, WP is a screening, signaling, and marking tool. It wouldn’t surprise me one bit though if those marking rockets get used for a different purpose.

It burns very hot, is toxic, is sticky, and can’t be easily extinguished- it will keep burning even after being doused with water.

Have you played Spec Ops: The Line?

I didn’t even know what White phosphorus was before playing it and now I don’t wanna anywhere nearby that.

When white phosphorus is used as a weapon of war, it is extremely dangerous because it can cause severe burns and is highly poisonous.

If you want to actually see white phosphorus burning then I’d highly recommend this video by Explosions&Fire: https://www.youtube.com/watch?v=ud1c5w06Y5E