The World's Top Ten Deadliest Chemical Weapons

The World's Top Ten Deadliest Chemical Weapons

by Aden Tate

The modern world is filled with weaponry that you don’t even have to see to be killed by.

Warfare is no longer relegated to the warrior, but is open to the scientist as well. And in many cases, a reasonably-competent chemist can create something that can kill more people than any soldier with a machine gun could ever hope to.

It doesn’t take a cloud of bullets to cause mass death. Now, all it takes is a cloud. This is where the world of chemical weapons enters the fray. Chemical warfare agents (CWA) made their brutal introduction in modern theaters at the Second Battle of Ypres in World War I.

Although many in the developed world think of chemical warfare as a relic of the past, the threat from these agents never truly went away. If anything, the risk of being a victim of chemical weapons has only increased with time.

Part of the problem is that the general population lacks knowledge regarding chemical weapons. You can’t prepare to survive a threat you don’t even know is out there. To illustrate some of the dangers of CW, we will be delving into a short list of chemical agents examples, how these common chemical weapons have been used, breaking down how they work, how they can harm you, and what to do to protect yourself against them.


  • 01

    What is Chlorine Gas?

  • 02

    What is Mustard Gas?

  • 03

    What is Phosgene?

  • 04

    What is Lewisite?

  • 05

    What is Hydrogen Cyanide?

  • 06

    What is Tabun?

  • 07

    What is Sarin Gas?

  • 08

    What is Soman?

  • 09

    What is VX Gas?

  • 10

    What is Ricin?

  • 11

    What about the Chemical Weapons Convention?

  • 12

    What is the Best Defense against Chemical Weapons?

  • 13

    Chemical Warfare Never Went Away


The very first modern chemical warfare agent ever used was chlorine gas. During World War I, trench warfare had resulted in a stalemate at Ypres, Belgium. Using technology developed by Nobel laureate Fritz Haber, the Germans released canisters of chlorine gas on the battlefield, and a new form of warfare was born.

Fritz Habor (no rights reserved)

Allied forces noticed a yellow-green cloud that was darker near the ground and lighter at the top, and it was heading their way. Moments later, many of these observers were asphyxiated.

Chlorine is the most prevalent chemical weapon. As it is widely used in a gamut of peacetime applications (e.g., swimming pools), every nation with chemical factories is likely to have chlorine readily available.

In addition, chlorine is a vital component in the manufacturing of most other chemical weapons. If a nation is known to have more potent CW agents, such as sarin, tabun, or mustard, it is virtually guaranteed to have chlorine gas agents as well.

Historical Fact

Fritz Haber’s wife was so distressed that her husband had initiated chemical warfare that she killed herself with a gunshot to the heart.

Like many chemical warfare agents, chlorine is heavier than air, so it hovers close to the ground. That is why soldiers feared it throughout World War I. Hiding in a trench protected them from machine gun and artillery fire, but it was absolutely useless against chlorine gas.

To counter this, many soldiers would pee on rags and breathe through them as the urine helped neutralize the chlorine.

1918 gas attack in France (no rights reserved)

Chlorine has a tell-tale noxious odor that most people associate with bleach, which contains chlorine. That odor led to it largely being abandoned as a CW agent. Gas masks worked great to protect troops from chlorine because as soon as they smelled the slightest trace of chlorine, they had sufficient time to don their masks and protect themselves.

What does Chlorine gas do to you?

Most people will know they’ve been exposed to chlorine because of its pungent odor. Victims of chlorine poisoning experience blurry vision, burning of the skin, nose, throat, and eyes, coughing, chest tightness, wheezing, and shortness of breath.

As time progresses, blisters may develop on the skin, and fluid can begin to accumulate in the lungs within a matter of hours. If left untreated, death due to asphyxiation can result.

Painting of a gas attack in WWI

What is Mustard Gas?

Throughout WWI, mustard gas or HD was referred to as the “king of the war gasses.” Known for its pungent garlic odor, this oily liquid was readily absorbed through the skin, meaning that unless a solder was completely protected head to toe, he would soon be incapacitated.

Mustard gas is persistent, meaning that once it is sprayed, it can stick to things for weeks. Even handling mustard-contaminated tools with bare hands days later can cause severe damage to the hands.

Mustard gas blister test from 1940

Historical Fact

Mustard munitions are marked with a single yellow ring.

While mustard gas is considered a first-generation chemical weapon (as are all WWI-era chemical weapons), it was used well after WWI ended. In 1936, Benito Mussolini dropped mustard bombs on what is now modern-day Ethiopia.

Mustard gas attack in the second Italo-Ethiopian War

Egypt also used mustard gas in June 1963 against the village of Al-Kawma, and it was used heavily by Saddam Hussein against Iran during the Iran–Iraq war. Although many Iranians were equipped with gas masks as the war progressed, their beards precluded a proper seal (just two days of beard growth will prevent a good gas mask seal).

What can Mustard gas do to you?

Within 3–24 hours after exposure (with a mean time of 10–12 hours), victims experience the first signs and symptoms of mustard poisoning. Burning, itching, and redness of any skin exposed to mustard gas is the first sign. Within 24 hours, all of those exposed areas will have developed enormous and incredibly painful blisters.

Canadian soldier with mustard gas burns from WWI

Even a minor dose can cause blindness for up to 10 days, eye pain, and light sensitivity. However, the effects of mustard gas don’t simply resolve. Chronic conditions, such as lung cancer and permanent blindness, can develop.

Death occurs by asphyxiation, as mustard gas severely inflames lung tissue. Thankfully though, mustard gas isn’t as lethal as many other CW agents. During WWI, only 5% of mustard gas victims received a fatal dose. Although there is no antidote to mustard gas poisoning, getting away from the gas and receiving prompt and appropriate medical care quickly provides a very solid chance of a full recovery.

What is Phosgene Gas?

Another first-generation chemical weapon, phosgene or CG is 18x more toxic than chlorine but is initially less irritating. Because it smells like freshly cut hay, troops were less likely to recognize it as a chemical weapon attack until they had already breathed in a lethal dose, making this a particularly deadly CW.

It wasn’t the “King of the Gasses,” but phosgene killed more people in WWI than any other CW agent. It’s commonly found in the manufacturing processes for plastics and pesticides, and it spreads very rapidly once released.

WWII Phosgene poster (no rights reserved)

Winds can carry phosgene upwards of 20 miles, meaning that even people nowhere near the site of the release can still potentially be harmed by this gas.

What can Phosgene do to you?

Within 2–6 hours after exposure, victims begin to experience coughing, blurry vision, and burning in the throat and eyes. Lesions on the skin akin to frostbite will begin to develop as well. Blood pressure may drop, and heart failure is possible.

Fluid will begin to accumulate in the lungs, and the victim will start to cough up a white/pink fluid indicative of pulmonary edema. Severe lung damage takes place, and the victim will asphyxiate if enough of the gas is inhaled.

If the patient recovers, they are apt to develop chronic bronchitis and emphysema—characteristics of COPD (chronic obstructive pulmonary disease, which is what long-term smokers develop).

What is Lewisite?

Lewisite or L is a rare example of a weapon that was designed to be used during WWI but was never actually released. By the time it was ready for battlefield use, the war was over. Designated “L” by the military, lewisite has no other purpose than as a CW agent.

Despite its telltale scent of geraniums, its purpose is anything but flowery, as lewisite causes severe damage virtually upon contact with human skin.

1923 British soldier in gas mask (no rights reserved)

What does Lewisite do to you?

Within 15–30 minutes after exposure, the skin begins to redden and become painful. Within hours, painful and grotesque blisters develop. If lewisite comes into contact with the eyes, severe pain and swelling result. Depending on the dose received, permanent blindness is possible.

If inhaled, shortness of breath, coughing, and a hoarse voice will occur, and the victim experiences diarrhea and vomiting. A condition known as “Lewisite shock” may appear because arsenic is naturally present in lewisite. This arsenic causes many symptoms of arsenic poisoning, one of which is dangerously low blood pressure.

While lewisite-caused blisters thankfully heal much faster than those caused by other CW blister agents, chronic respiratory conditions are possible.

What is Hydrogen Cyanide?

Also known as prussic acid, many people are familiar with the most common variant of hydrogen cyanide (AC): Zyklon B. This was pumped into the German gas chambers as part of Hitler’s “Final Solution” during the Holocaust. Originally, Zyklon B was developed as a rodenticide. Many chemical weapons originated from pesticide research, and it wasn’t long until it was realized that if Zyklon B works on rats, it would also work on humans.

Zyklon B canisters (common domain)

More recently, Saddam Hussein dropped CW gas, probably hydrogen cyanide (also called “AC”), on the Kurdish city of Halabja, during the Iran–Iraq War.

This is a very potent chemical weapon that smells like rancid almonds, but only 20% of people reportedly have the capacity to discern the smell.

What can Hydrogen Cyanide do to you?

Hydrogen cyanide works by binding to oxygen receptors in the body, preventing cells from utilizing oxygen.

When inhaled, hydrogen cyanide causes dizziness, vomiting, headache, a fast heart rate/breathing, and weakness.

As blood pressure plummets, the chance of passing out increases. Inhalation of large doses causes convulsions and respiratory failure until death is the final result.

What is Tabun?

In 1938, German scientist Gerhard Schrader accidentally created one of the deadliest chemical weapons of his time while trying to create a better pesticide. The end result was tabun. Named after the German word for “taboo,” this particular weapon was soon manufactured throughout the world.

Tabun is a nerve agent, and although it’s relatively antiquated, it isn’t any less deadly. Not only can tabun be absorbed through the skin, but it’s five times as toxic as DFP (a cousin of sarin). It’s tasteless, colorless, and has a slightly fruity odor. Few know they’ve been exposed to it until it is too late.

Historical Fact

At one time, Syria had SS-21 missiles with nerve agents aimed at Tel Aviv. These types of chemical weapons aren’t as uncommon as one may be led to believe.

This is another CW agent that is rather persistent and can even be spread via contact with contaminated clothing.

Because of these features, Saddam Hussein used it against the Iranians during the 1980s to great effect.

Saddam Hussein

What can Tabun do to you?

Like all CW agents, the larger the dose, the more severe the consequences.

Even exposure to low concentrations results in fatigue, apathy, and loss of interest in life. Extremes of blood pressure (high or low), blurry vision, constricted pupils, eye pain, headache, rapid breathing/heart rate, vomiting, drooling, sweating, and excessive urination are all common. A cough, chest tightness, sleepiness, weakness, and muscle twitching are also prevalent.

If the dosage is high enough, the victim will violently convulse, lose consciousness, become paralyzed, and then die from respiratory failure.

Tabun is particularly nasty in that it can have a cumulative effect. It takes a long time for tabun to break down in the body, and so repeated low-dose exposures can eventually result in an acute response (e.g., death).

What is Sarin Gas?

Sarin is yet another chemical weapon the Germans tested against concentration camp inmates during WWII. Victims were told that if they survived a sarin test, they would “win” their freedom. It is highly doubtful that any of them won their freedom this way.

Being six times more potent than tabun, sarin is incredibly deadly. Breathing air that contains just one parts per million of sarin will kill a man within 10 minutes. Sarin has no odor and is incredibly prone to evaporation. While it can be spread via contaminated surfaces, its high volatility means that it does not stick around.

Historical Fact

In 1953, it was theorized that a single Soviet TU-4 bomber loaded with sarin bombs (and they had plenty of them) could actually kill more people than an atomic bomb in many instances.

While Saddam Hussein had sarin gas, the heat of the desert made it less effective than other chemical weapons. Regardless, on January 19th of the first year of the Gulf War, Czech soldiers within Iraq detected low levels of sarin in the air.

The ease with which sarin can be made and its high evaporation rate were why the Aum Shinrikyo cult in Japan used this CW for several attempted murders. After a failed anthrax attack, Aum Shinrikyo tested sarin gas on sheep they owned at a farm in Australia (they had members around the world). After these tests were successful, they attempted to assassinate a number of Japanese judges using a van-mounted sarin mist gun.

Overhead view of Aum Shinrikyo’s CW plant (no rights reserved)

They missed their intended target because of various mishaps, but ended up murdering seven and hospitalizing 54 accidentally. As police moved in on the cult, Aum Shinrikyo moved on to larger actions to try to buy themselves time.

These actions culminated in the Tokyo subway attacks. The cult filled 11 hospital IV bags with sarin, wrapped them in newspaper, and then stabbed them with sharpened umbrellas on subways during rush hour.

Twelve people were murdered, and over 1,000 were injured.

Response to the Tokyo subway attack (no rights reserved)

What can Sarin gas do to you?

Even low-level exposure to sarin can result in long-term health consequences. Gulf War Illness is widely believed to be due to sarin (GB) exposure during the Gulf War. While there weren’t any chemical attacks during Operation Desert Storm, CW detectors throughout Iraq went off thousands of times as American jets bombed factories known for manufacturing CW.

Sarin and cyclosarin plumed into the air as a result of these air strikes, and wind analysis shows that these gasses could have been carried up to 300 miles away.

Now, somewhere between 100,000 to 696,000 soldiers from the Gulf War have reported chronic fatigue, headaches, memory loss, and muscle pain—all symptoms of low-level sarin exposure.

Just a small dose of sarin causes constricted pupils, eye pain, blurry vision, drooling, excessive sweating and urination, watery eyes, runny nose, vomiting, a cough, chest tightness, rapid breathing/heart rate, extremes of blood pressure, headache, confusion, and weakness.

If the exposure is great enough, violent convulsions, loss of consciousness, paralysis, and respiratory failure will lead to death.

Historical Fact

Cornelius Ryan’s 1953 article “G-Gas: A New Weapon of Chilling Terror” said that a single bomber filled with sarin bombs would kill more people than an atomic bomb in many instances.

What is Soman?

Invented by Richard Kuhn, soman is sarin on steroids. Not only is it twice as toxic as sarin gas, it’s more persistent as well. It is readily absorbed through the skin, so simply moving through an area that was sprayed days before is enough to kill.

Soman is clear, colorless, and tasteless, but it does have a very faint odor of mothballs or rotten fruit.

Iraq used this often throughout the Iran–Iraq War as it was less volatile than sarin. Typically, the Iraqis mixed soman with a chemical weapon called cyclosarin to create a cocktail that worked better in the desert heat (as stated before, other agents evaporated too quickly).

Iranian soldier with gas mask in Iran–Iraq War

What does Soman do to you?

Soman poisoning has the same symptoms as sarin poisoning. Pinpoint pupils, eye pain, blurry vision, drooling, excessive sweating and urination, watery eyes, runny nose, vomiting, a cough, chest tightness, rapid breathing/heart rate, extremes of blood pressure, headache, confusion, and weakness.

If the exposure is sufficient, violent convulsions, loss of consciousness, paralysis, and respiratory failure will lead to death.

Soman, like most nerve agents, works by inactivating a molecule called cholinesterase within the human body. The problem with soman, though, is that it not only inactivates this compound but effectively destroys it after two minutes. Earlier nerve agents were treated with atropine injections. With soman, atropine isn’t effective, so the prospects of surviving a soman attack are grim.

Historical Fact

Pyridostigmine bromide (PB) tablets offer some protection from soman by preemptively binding to cholinesterase and creating a reserve for later release. American troops were given these tablets before the Gulf War invasion to protect them in the likely event of an Iraqi soman release.

What is VX gas?

One of the most lethal CW weapons ever created is VX. Compared with sarin, VX is three times as toxic if inhaled and 1,000 times as toxic if it comes into contact with the skin. VX is incredibly persistent in the environment, able to remain lethal up to three weeks after being sprayed in an area. It easily passes through clothing to the skin, and victims don’t know that they’ve been exposed until it’s too late, as VX is both odorless and tasteless.

It is a completely clear liquid (amber if it’s not pure) and like soman, it is not treatable with atropines.

Aum Shinrikyo manufactured their own VX in addition to anthrax and sarin. They assassinated a former member who threatened to reveal their activities to the police by sprinkling a small amount of it onto the back of his neck as he was jogging. The victim chased his assailants for 100 yards before he collapsed, and he died days later.

What does VX do to you?

VX is a “V” agent, all of which operate in roughly the same manner. The telltale sign of VX exposure is the pupils constricting to a pinpoint. Victims’ eyes almost lack an pupil due to the level of constriction. Dimmed and blurred vision is a natural consequence of this.

Sweat, snot, and spit production all increase dramatically, and the digestive tract involuntarily contracts, resulting in nausea, vomiting, uncontrollable diarrhea, and severe abdominal cramps.

As the smooth muscle in the respiratory passages constricts, the victim slowly loses the ability to breathe—as if they’re suffering a severe asthma attack. Muscular contractions are severe, with parts of the muscle contracting so fiercely that it looks as if worms are wriggling underneath the skin. This occurs as violent and painful convulsions take place.

Death rapidly follows, typically due to asphyxiation following respiratory arrest.

Chronic, low-dose exposure leads to insomnia, inability to make decisions, high levels of anxiety, mood swings, mental fogginess, and bizarre dreams.

Historical Fact

There is a Russian version of VX known as R-33. Though it’s largely the same chemical compound as American-made VX, the molecular geometry of R-33 is different. It is theorized that this geometric difference is so that R-33 won’t show up on American-made CW detectors.

R-33 is incredibly deadly, “aging” cholinesterase much faster than VX, and making successful treatment for R-33 poisoning highly unlikely.

What is Ricin?

Naturally found in castor beans, ricin can be administered either as a powder, mist, or pellet. Originally developed for CW in the 1940s, ricin soon became prevalent as a chemical weapon throughout the world. In 1978, Bulgarian journalist Georgi Markov was assassinated via ricin in London. A man with a weaponized umbrella attacked Markov, using the umbrella to inject a ricin pellet.

Castor bean

A few years later, there was evidence that Saddam Hussein used weaponized ricin during the Iran–Iraq War.

Aussie soldier inspecting Iraqi soldiers, all with gas masks (no rights reserved)

What does Ricin do to you?

At the cellular level, ricin blocks the proteins that cells need to survive. If one inhales ricin, fever, blue skin, cough, heavy sweating, low blood pressure, and fluid filling the lungs result.

If ricin is eaten, vomiting, diarrhea, bloody stools and urine, low blood pressure, seizures, and organ failure occur.

In either case, death takes place within 36–72 hours.

What about the Chemical Weapons Convention?

In 1997, a number of nations signed what is called the Chemical Weapons Convention or the CWC. This international agreement states that these nations would neither develop new chemical warfare agents nor stockpile them anymore.

However, many of the nations that signed the CWC are suspected of developing new CW agents, and many nations never signed it. Even if they had, there is no telling if they kept their word.

Pretending that CW won’t be used—whether in conventional warfare or by a terrorist group—is a naïve notion at best.

What’s the Best Defense against Chemical Weapons?

The best defense is a quality gas mask, a proper filter, and a full HAZMAT suit. Years of warfare have proven this. When soldiers are moving through an area of a suspected CW release, this is exactly what they wear. If you believe that you might be in an area where chemical warfare agents could be used, this is what you’re going to want to use as well.

MIRA Safety CM-6M Tactical Gas Mask - Full-Face Respirator

CM-6M Full Face Respirator

At the very least, a proper chemical, biological, radiological, and nuclear (CBRN) rated gas mask and filter are a must. The Tokyo sarin subway attacks affected so many people because they were inhaling it. Although sarin can easily be absorbed through the skin, the manner of release during the subway attack made inhalational injuries the primary issue.

The MIRA Safety CM-6M is the perfect gas mask for chemical warfare and could potentially save thousands of lives during such an event. The bromobutyl rubber construction and the polycarbonate visor offer full-face protection against even blistering agents like mustard gas. In addition, the prevalence of chlorine-producing facilities worldwide means a gas mask is a minimal precaution against a chlorine gas release (intentional or otherwise).

For more information on the best gas mask options available today, check out our Definitive Gas Mask Buyer's Guide.

MIRA Safety NBC-77 SOF CBRN Filter

NBC-77 SOF Filter

Filter selection is vital when it comes to proper protection against chemical warfare agents. The MIRA Safety NBC-77 SOF filter is among the highest grade of filtration currently available. This canister is rated to protect users from everything from CS gas, ammonia, chlorine, to mustard, phosgene, sarin, and even VX gas. The 20-year shelf life offers users a great long-term investment in their personal protection.

For a breakdown on the various types of filters, read our Gas Mask Filters Buyer's Guide.


If moving through an area where you suspect V agents or more persistent gasses have been or will be used, we highly recommend the MIRA Safety HAZ-SUIT. As discussed above, a number of CW agents can transfer to the bloodstream or spread to other people through clothing.

A HAZ-SUIT is an impenetrable layer of protection that keeps hazardous CW agents away from the skin and clothing, thereby keeping the wearer safe. We strongly recommend considering one if you live in an area where chemical warfare or terrorist attacks are likely.

For a comparison of the most widely used hazmat suit options, read our Hazmat Suit Buyer's Guide.

MIRA Safety M4 Military Poncho

You can also further augment your protection with the MIRA Safety M4 Military Poncho. Unlike ordinary ponchos, this is specifically designed to shield you and your equipment from chemical weapon exposure. An often ignored aspect of the deployment of CWs is that evaporation of water sources and the eventual precipitation can produce chemically mixed rain water. In this instance, doubling up your HAZ-Suit with this poncho will further increase your survivability.

Chemical Warfare Never Went Away

It simply disappeared from the limelight.

Chemical warfare agents are still out there and will most certainly be used again, but that doesn’t mean the case is hopeless. There are steps you can take to keep yourself and your family safe. And MIRA Safety can help you to survive these attacks with their best in class, professional-grade personal protective equipment that will help you avoid becoming another victim of a chemical weapon attack.