About Tear Gas


The Ban Against Chemical Weapons in War

The struggle to eradicate the use of chemical weapons in international warfare has spanned centuries. International agreements to prohibit the use of chemical weapons have shaped the “rules of warfare” that are still in practice today. These efforts were escalated after the horrors of large-scale chemical warfare seen during World War I, culminating in the creation of the 1925 Geneva Protocol. The Protocol is now a binding part of International Law for signatory States, preventing the use in war of any asphyxiating, poisonous or other gases, and of bacteriological methods of warfare.

The US’s Exception Meets International Protest

Until the Presidency of Richard Nixon, the United States maintained an interpretation of the Protocol that excluded the use of tear gas and herbicides, which were essential elements to the US’s military strategy during the Vietnam War. These actions caught the attention of international activists and politicians who denounced the use of tear gas and herbicides as a violation of the Protocol and called for recognition by the United States that the Protocol covered the use of ALL chemical and biological weapons. A resolution to the Protocol condemning their use was adopted on December 16, 1969, by a vote of 80-3; the 3 oppositions being Australia, Portugal, and the United States. In 1974, the Ford Administration launched an initiative to obtain Senate consent to ratify the Protocol, denouncing the first use of riot-control agents (including tear gas and pepper spray) and herbicides in war. The Protocol and the Geneva Convention were ratified by President Ford on January 22, 1975.

The Chemical Weapons Convention

With this increase in international attention towards the use of chemical weapons, the 1978 Geneva Conference structured its agenda around the issue. Specifically, a US-Soviet working group set the stage for the formulation of the Chemical Weapons Convention (CWC)—highlighting the need to establish a conference or committee of all states parties to oversee implementation. A draft text was opened for signature on January 13, 1993, with 130 signatory states within the first two days. The signatories further approved a resolution to set up what would later become the Organization for the Prohibition of Chemical Weapons (OPCW), which is responsible for the regulation, implementation, and verification of the CWC. In April of 1997, the CWC entered into force with 87 States Parties - becoming binding international law prohibiting the development, production, stockpiling, and use of chemical weapons.

The Latest Exception: “Riot Control Agents”

Riot control agents including tear gas and pepper spray are banned in international warfare under both the 1925 Geneva Protocol and the Chemical Weapons Convention (CWC). The CWC defines chemical weapons as “munitions and devices that are designed to cause death or other harm through toxic chemicals” that lead to “death, temporary incapacitation or permanent harm to humans or animals.”  While tear gas and pepper spray, under international law, are banned as a “method of warfare”, there are no restrictions to their domestic use as a “riot control agent.” According to the CWC, “riot control agents” are any chemicals which are not specifically listed in their list of prohibited chemicals and that can cause in humans rapid “sensory irritation or disabling physical effects which disappear within a short time following termination of exposure.”  Under Article II Section 9 of the CWC, the use of such chemicals for “law enforcement including domestic riot control purposes” is not prohibited under the Convention.

We believe that tear gas is a weapon of war against the people. We believe that tear gas remains a chemical weapons whether it is used on a battlefield or in the city streets. It has hurt and killed people globally as a part of government crackdowns on popular dissent, whether in the streets or inside prisons, as ever-increasingly militarized police forces continue to bring the battle home. Whether the signatories of the CWC agree, we know that tear gas is a method of warfare.




What is Tear Gas? What Are “Lachrymatory Agents”?

The term “tear gas” is applied to numerous substances, although the most common one currently in use internationally is what is called “CS gas.” CS is one of many so-called “nonlethal” chemical weapons referred to as “lachrymatory agents” (which comes from “lacrima,” the latin word for “tear.”) The category “lachrymatory agents” also includes chemicals commonly known as pepper spray (OC, PAVA) and mace (CN). Technically, tear gas and pepper spray are thought of as different substances. (For instance, most people probably think of tear gas as a gas and pepper spray as a liquid, however either chemical can come in various forms depending on how it is prepared.) However, they are both lachrymatory agents used by the state to stifle dissent and to terrorize prisoners, and they are often manufactured by the same companies (sometimes they are also combined in the same product.)

The term “tear gas” is a misnomer. For one thing, “tear gas” seems to imply something innocuous— you would think it’s just a chemical that makes you tear up. In fact, tear gas is a dangerous, potentially lethal chemical agent which is outlawed under the Chemical Weapons Convention for use during wartime. As the Omega Research Foundation argues: “Less-lethal weapons are presented as more acceptable alternatives to guns. But these weapons augment rather than replace the more lethal weapons. Euphemistic labels are used to create the impression that these weapons represent soft and gentle forms of control. CS is never referred to by the authorities as vomit gas, in spite of its capacity to cause violent retching.” NGO Physicians for Human Rights believes that “ ‘tear gas’ is a misnomer for a group of poisonous gases which, far from being innocuous, have serious acute and longer-term adverse effects on the health of significant numbers of those exposed.” We aim to change the conversation on tear gas by calling this so-called “nonlethal” weapon what it is: a chemical weapon. We view tear gas, pepper spray, and all “lachrymatory agents” and so-called “non-lethal weapons” as chemical weapons in the war on democracy.

It’s important to note that “tear gas” is not actually a gas. The active chemicals in all different kinds of tear gas and pepper spray are solid at room temperature, and need to be mixed with other chemicals in order to produce what is called an aerosol— solid particles finely dispersed in the air, similar to smoke or a cloud. They can also be dissolved in liquid solution, which is how pepper spray is commonly used. This is significant since the symptoms and treatment for tear gas and pepper spray exposure can vary depending on the kind of aerosolizing agents or solvents used. For example, when silica gel is added to CS to form CS1 or CS2, the result is a stronger tear gas which is more water resistant. Methylene chloride— a known carcinogen— was used as a solvent in the tear gas and pepper spray against WTO protesters in Seattle in 1999. This is believed to have caused many health problems for protesters who were exposed.


Photo Credit: CAAT: Campaign Against the Arms Trade

CS, CS1, CS2 - Most common form of teargas

2-Chlorobenzalmalononitrile (also called o-chlorobenzylidene malononitrile) (chemical formula: C10H5ClN2), commonly known as CS.

CS is by far the most common form of teargas used. CS can be combined with silica aerogel to form CS1 and CS2, “which increases the fluidity and water resistance” as well as the intensity of the symptoms. CS was first developed in 1928 by US scientists Ben Corson and Roger Stoughton, and it is named after their last initials.

CN - commonly referred to as “mace”, also called “tear gas”

Chloracetophenone (also called Phenacyl chloride or 2-chloro-1-phenylethanone) (chemical formula: C8H7ClO), more commonly known as “mace.”

CN is far more toxic and intense than CS, and is known to be able to cause permanent eye damage. Although CN is more commonly known as "mace," it is also referred to as "tear gas."

CR- also called “teargas”

Dibenz (b, f)-1, 4-oxazepine, or Dibenzoxazepine.

CR is far more intense and toxic than CS. For this reason, CR has largely, although not entirely, been replaced by CS.

OC and PAVA- "pepper spray."

8-Methyl-N-vanillyl-trans-6-nonenamide (OC, chemical formula C18H27NO3) and N-[(4-hydroxy-3-methoxyphenyl)methyl]nonanamide (pelargonic acid vanillylamide, PAVA, chemical formula C17H27NO3), more commonly known as “pepper spray.”

OC is actually derived from chili peppers, whereas PAVA is a similar chemical which is made synthetically.




This section is intended to provide a reference for activists about various US laws that could be useful for activists to combat US sales of tear gas and other weapons to governments abroad. We do not necessarily agree with or endorse the rationale behind many of these bills (such as the distinction between “legitimate” and “illegitimate” forms of state violence), but we provide these sources for the reference for activists.

Leahy Law on Human Rights- 1997 (Section 620M of Foreign Assistance Act)

Named after US Senator Patrick Leahy, the Leahy Law on Human Rights was passed in 1997 as an amendment to the Foreign Assistance Act of 1961. The provisions, which can be found under Section 620M, are concerned with both US Department of State legislation covering all “assistance” (as it applies under the FAA and the Arms Export Control Act of 1976) and the Department of Defense “training programs” funded under the Defense Department Appropriations Acts. If a foreign country applies to receive “assistance” or “training”, the Leahy Law subjects them to a rigorous vetting process. Supposedly, this process determines whether the concerned government agency has committed violations of human rights. According to the law, when evidence which the US government deems “credible” exists of human rights abuses by foreign regimes, all US aid to said regime must stop. This applies to: foreign militaries, reserves, police, homeland security forces, prison guards, and other units or individual members of units authorized to use force. This applies to all “assistance” under the Foreign Assistance Act. It should be noted, however, that the Leahy law applies only to what is called “Foreign Military Sales,” (FMS) and not to what is called “Direct Contract Sales” (DCS.) In other words, there are tremendous limitations to the Leahy law.

Under the Leahy law, any foreign government that wishes to purchase weapons through FMS is subjected to what is called a “vetting process.” The full text of the law, and a breakdown of the vetting process, can be found here. Briefly, the vetting process begins with the embassy of the country of the individuals or units in question, where information is gathered from governmental, nongovernmental, and media resources. According to the law, if any derogatory information is uncovered, the country can be suspended from assistance. If not immediately denied, the “Bureau of Democracy,” a branch of the US Department of State, augments the information gathered from the respective embassy and further investigates the human rights abuses  and can then accordingly prohibit training or assistance, as permitted by the Leahy Law. If a decision is still not reached, the State Department reviews further negative information while the assistance in question remains on hold until the State Department makes the final call of authorization or denial.


Foreign Military Sales (FMS) and Direct Contract Sales (DCS)

As mentioned above, the “Leahy Law” is only applicable to Foreign Military Sales (FMS), not to the more heavily used Direct Commercial Sales (DCS). Foreign Military Sales are facilitated by the US Department of Defense and cover the sales of US arms, training, and other defense equipment to foreign governments, while Direct Commercial Sales are sales in which foreign governments buy directly from US weapons manufactuerers.  FMS is an entirely governmental process, where the vetting process applies. DCS includes the sale and transfer of weapons and other defense articles, services, and training between private US companies and foreign recipients. FMS is far more regulated than DCS. As international exports, DCS must meet all eligibility requirements, such as valid export licenses and permissibility of materials, contained in the Arms Export Control Act and the International Traffic in Arms Regulations. Furthermore, the US is required by Congress under the FAA to prepare an annual report on this category of military assistance and exports (a provision made possible in part by Senator Leahy). These ‘655’ reports are the most detailed account available of specific Direct Commercial Sales of US weapons exported to governments or private buyers around the world. The 655 report, as called for by the Foreign Assistance Act of 1961, is compiled from the annual records of the State Department and each yearly report can be found online at www.pmddtc.state.gov.




Health effects of tear gas and pepper spray:

Although the Chemical Weapons Convention (CWC) prohibits the use of tear gas and pepper spray in warfare, for domestic policing and related uses by state forces, these chemicals are allowed to be used on people and are labeled as “riot control agents.” The CWC stipulates that these chemical weapons must have effects that disappear shortly after exposure, meaning no long-term health effects; however, in a number of cases, researchers have linked the use of tear gas and pepper spray to possible serious illness and death. This research echoes people’s stories about tear gas and pepper spray.

In cases of the use of tear gas and pepper spray as the central element of a state offensive against people protesting in the streets and/or expressing their dissent to the conditions in which they live, people who have been assaulted with large amounts of tear gas and pepper spray, sometimes for a prolonged period of time, have reported acute and long-lasting health effects. During times like the 1987 government attack on the people of South Korea during a wave of protests where 351,000 tear gas canisters were used against demonstrators in multiple cities, or the massive use of tear gas in Quebec City in Canada in 2001 during the Free Trade Area of the Americas protests, or with the near-daily use of tear gas against people in struggle in Bahrain, Egypt, and Palestine, again in multiple cities/towns, people have reported severe health problems. In the case of Bahrain, Egypt, and Palestine, there have been many reported deaths (54 in Bahrain alone since 2011) due in some cases to tear gas canisters (the most common being CS gas) being fired at a high velocity as projectile weapons, though in other cases it is due to the exposure to the gas itself.

Experiences reported beyond the immediate effects of the tear gas include coughing, shortness of breath, and other lung-related problems (heighted in people who already have lung problems), delayed menstruation, and reports of miscarriages and stillbirths associated with the gas. These effects have also been reported in research studies, along with reports that tear gas can also cause damage to the heart and liver. In the case of pepper spray, deaths have similarly been reported (mostly in jails and prisons) due to exposure to pepper spray that is well over the “recommended” amount from the manufacturer and is used in an enclosed space and/or over prolonged periods of time. One infamous news story from 1995 reports the LA Police Department as admitting that, over a 5-year period, 61 people died while in police custody as the result of the use of pepper spray. Again, prior lung problems heighten the danger of this chemical weapon. There have been few research studies of the health effects of pepper spray, which means there is much less documentation of its longer-term effects beyond those cases of death which sometimes become public. Many continue to call for more clinical research studies about the health effects of pepper spray and tear gas.

It’s important to note that in the case of tear gas, because the nature of this weapon, that in the cases of the use of the gas as a primary tool of state repression, longer-term health effects (lasting at least a week to becoming a chronic condition) were also experienced by people who were not in direct contact with police forces, which means that the health effects of tear gas can spread to people who were not at the scene at the time or were the intended target of its use.

It’s also important to note that “tear gas” is not actually a gas. The active chemicals in all different kinds of tear gas and pepper spray are solid at room temperature, and need to be mixed with other chemicals in order to produce what is called an aerosol— solid particles finely dispersed in the air, similar to smoke or a cloud. They can also be dissolved in liquid solution, which is how pepper spray is commonly used. This is significant since the health effects of tear gas and pepper spray exposure can vary depending on the kind of aerosolizing agents or solvents used. For example, when silica gel is added to CS to form CS1 or CS2, the result is a stronger tear gas, which is more water resistant. Methylene chloride— a known carcinogen— was used as a solvent in the tear gas and pepper spray used against WTO protesters in Seattle in 1999. This is believed to have caused many health problems for protesters who were exposed.

Part of the problem is that the health effects of tear gas and pepper spray have not been researched thoroughly enough, and often what research has been done has been funded by or otherwise influenced by the very manufacturers who produce these weapons. One notorious example of this kind of corruption took place in Chile. On May 18, 2011, the Chilean government announced— in the wake of a study by the University of Chile which demonstrated that CS exposure may lead to miscarriages— that they would temporarily suspend the use of tear gas throughout the country. Latin America News Dispatch quotes then-Interior Minister Rodrigo Hinzpeter as saying: “[I]t seems reasonable to suspend the use of tear gas until new medical reports dispel any doubts about the appropriateness of employing these gases to confront situations of public disorder and vandalism.” Fortunately for the Chilean government— and unfortunately for Chilean protesters, such as the 30,000 protesters who, a week earlier, had gathered to demonstrate against the HidroAysén hydroelectric project and been faced with tear gas— the government found exactly the evidence they were looking for, from the manufacturers themselves! The Chilean government put together a report, three days later, citing US company Combined Systems International (supplier of tear gas to the Chilean police), arguing that tear gas was safe. The report, and the lifting of the ban on tear gas, came just in time for the state to use tear gas against the next round of HidroAysén protests.

There is a similar story about how pepper spray got approved within the US for use by law enforcement. According to a report by Earth First! Journal: “[P]epper spray was originally introduced in the U.S. in the 1980s by the Postal Service as a dog repellent... The FBI endorsed it as an ‘official chemical agent’ in 1987 but it wasn't until 1991 that more than 3,000 local law enforcement agencies added it to their arsenals. This surge of interest hinged on a widely-circulated and influential study by FBI special agent Thomas Ward. As the FBI's chief expert on OC, Ward peddled the painful stuff like he was in a state of police-state-hallelujah.

“On February 12, 1996, we find Thomas Ward pleading guilty to a single count felony for accepting a $57,500 ‘kickback’ from the manufacturers of Cap-Stun brand pepper spray. The second-largest company in the growing pepper spray industry, Cap-Stun also happened to be owned by Ward's very own wife, and, coincidentally, was the exact brand recommended by Ward as far back as the mid-'80s. Initially facing a $250,000 fine and five years in prison, Ward got off with two months in prison and three years probation. The FBI responded to his conviction by proclaiming it would continue using Cap-Stun since it was ‘unaware of any basis for finding that pepper spray is not...safe and effective.’ Ward's corrupt study is still cited today as justification for use of OC. Yet in Ottawa, Ontario; Berkeley, California; and Tucson, Arizona; police departments have chosen to stop using pepper spray due to the controversy (and costly lawsuits) it brings with it.”

In other words, these so-called “non-lethal weapons” are insufficiently researched, and the research that is out there is often pushed by the companies manufacturing the weapons in the first place. What little research there is that is not sponsored by the manufacturers themselves is often done against great odds, and it generally takes a mass deployment of tear gas on the part of a state for researchers to be able to conduct such research. For instance, two landmark studies which have been done on the longterm impact of tear gas exposure, both by the group Physicians for Human Rights, were done during or in the aftermath of uprisings. The first was the 1987 uprising in South Korea. The second is the recent and ongoing uprising in Bahrain. In the 1987 report, after outlining some of the vital research which needed to take place, the NGO concluded that there “is considerable evidence that these essential studies cannot be undertaken in South Korea today. The government has not allowed research by responsible medical investigators of this problem and has refused to identify for health professionals the chemical compounds it is using, thereby blocking essential medical studies and proper treatment.” 



Please be aware that there are many different kinds of tear gas and pepper spray, with different chemical properties, concentrations, and reactions. Different people may react differently to different remedies, and different kinds of tear gas or pepper spray may react differently to different remedies. The following is intended as a guide but is by no means definative. As we learn more we will attempt to keep this section updated.

To learn more about different kinds of tear gas and pepper spray, click here.
To learn more about what is known about the health effects of tear gas and pepper spray, click here.
If you have questions or concerns about the information below, or have more information we should be aware of, please, contact us.


How Tear Gas and Pepper Spray May Affect You [excerpted from/ partially based off of Starhawk's website, Activism Resources section, although we will update as we get more feedback]:

Teargassing protesters in Bahrain

Both tear gas and pepper spray are skin irritants, causing burning pain and excess drainage from eyes, nose, mouth and breathing passages. Pepper spray is more popular with authorities as an agent of control because of its immediate pain-causing qualities. It is harder to remove from the skin and has the capacity to cause first degree burns.

If you are exposed to either, you may experience:

  • stinging, burning in your eyes, nose, mouth and skin
  • excessive tearing, causing your vision to blur
  • runny nose
  • increased salivation
  • coughing and difficulty breathing
  • disorientation, confusion and sometimes panic 
  • intense anger from pepper spray exposure is a common response


For most healthy people, the effects of tear gas and pepper spray are temporary. However, for some people the effects can be long-lasting and life-threatening.

People with the conditions listed below should be aware of these risks and may want to try and avoid exposure if at all possible. Please be aware that police behavior is unpredictable, and avoidance is not always possible.



  • Folks with respiratory diseases, such as asthma, emphysema, etc. risk exacerbation, or permanent damage if exposed.
  • Vulnerable people such as infants, the elderly, and the immune compromised, risk intensified and possibly life-threatening responses.
  • Anyone with chronic health conditions or those on medications that weaken the immune system, (ie: chemotherapy, Lupus, HIV, radiation, or long-term corticosteroids such as prednisone) risk exacerbation of illness, intensified response and possible delayed recovery.
  • Women who are or could be pregnant, or who are trying to get pregnant, may be at risk of spontaneous abortion, or increased risk of birth defects. 
  • Nursing mothers risk passing toxins on to their infant.
  • Folks with skin conditions (ie: severe acne, psoriasis, or eczema) and eye conditions (ie: conjunctivitis or uveitis) risk an intensified response. 
  • People wearing contact lenses may experience increased eye irritation and damage due to chemicals being trapped under the lenses. CORRECTION: One of our contacts has informed us that tear gas exposure may cause contact lenses to FUSE to the eyes and cause PERMANENT BLINDNESS


  • Avoid use of oils, lotions and detergents because they can trap the chemicals and thereby prolong exposure. Wash your clothes, your hair and your skin beforehand in a detergent-free soap (such as Dr.Bronner's or most eco-friendly products).
  • Don't put vaseline, mineral oil, oil-based sunscreen or moisturizers on skin as they can trap chemicals. 
  • Don't wear contact lenses, which can trap irritating chemicals underneath. 
  • We recommend using a water or alcohol-based sunscreen (rather than oil-based). If your choice is between oil-based or nothing, we advocate using the sunscreen. Getting pepper sprayed on top of a sunburn is not fun.
  • We also recommend minimizing skin exposure by covering up as much as possible. This can also protect you from the sun, as can a big hat.
  • Gas masks provide the best facial protection, if properly fitted and sealed. Alternatively, goggles (with shatter-proof lenses), respirators, even a wet bandana over the nose and mouth will help.


  • STAY CALM. Panicking increases the irritation. Breathe slowly. 
  • If you see it coming or get a warning, put on protective gear, if able, try to move away or get upwind.
  • Blow your nose, rinse your mouth, cough and spit. Try not to swallow.
  • If you wear contacts, try to remove the lenses or get someone to remove them for you, with CLEAN, uncontaminated fingers.


We have been doing trials with pepper spray to find good remedies and have found some things will definitely help minimize the discomfort. None of these are miracle cures; using these remedies will help people to feel better faster, but it will still take time.

  • CORRECTION: One of our contacts has warned that using antacid on the eyes may actually worsen the effects, and that only water should be used as an eye flush. We are looking into this. For the eyes and mouth: We recommend a solution of half liquid antacid (like Maalox) and half water. A spray bottle is ideal but a bottle that has a squirt cap works as well. Always irrigate from the inside corner of the eye towards the outside, with head tilted back and slightly towards the side being rinsed. It seems from our trials that it needs to get into the eye to help. This means that if the sprayed person says it's okay you should try to open their eye for them. They most likely won't be able/willing to open it themselves, and opening will cause a temporary increase in pain, but the solution does help. It works great as a mouth rinse too. 
  • For the skin: We recommend canola oil followed by alcohol. Carefully avoiding the eyes, vigorously wipe the skin that was exposed to the chemical with a rag or gauze sponge saturated with canola oil. Follow this immediately with a rubbing of alcohol. Remember that alcohol in the eyes hurts A LOT. Anyone whose eyes you get alcohol in will not be your friend.
  • Secondary treatments can include: spitting, blowing your nose, coughing up mucous (you don't want to swallow these chemicals!), walking around with your arms outstretched, removing contaminated clothing, and taking a cool shower. In fact, it is essential to shower and wash your clothes (using a strong detergent) as soon as you are able. This shit is toxic, and will continually contaminate you and everyone around you until you get rid of it. Until then, try not to touch your eyes or your face, or other people, furniture, carpets etc. to avoid further contamination. 
  • Remember, its effects are often only temporary, and we are extremely strong.



The best protection against chemical weapons is a gas mask. Prices range from $25-50. The filters are harder to acquire. Any kind of mask should be tried on and sized.

When paired with goggles, respirators make an excellent alternative to gas masks. It is necessary to do some homework beforehand and find goggles that don't fog up and that fit tightly on your face with the respirator. Respirators can be purchased at safety supply or welding supply stores. Ask for filters for particulates and organic chemicals and tell the clerk what you're filtering to double check. Costs between $18-24.

A bandanna soaked in water or vinegar and tied tightly around the nose and mouth is a last resort. It is far better than nothing, but remember that it is merely a barrier and not a filter and so won't do much for long-term protection. You can keep it soaking in a plastic bag until ready to use. Bring several, as multiple uses will render a bandanna as gassy as the air around you.

For protecting your eyes, swim goggles work well, as they have a tight seal. Shatter-resistance is another nice quality for goggles to have. Most goggles have air holes to prevent fogging--fill these with epoxy. Covering these holes with duct tape can work in a pinch against an initial attack, though not for long term protection. Try them on with your respirator or bandanna to ensure that they are compatible and that both will provide a tight seal.


You should be aware that whatever protection you choose will be visually quite powerful. Gas masks work the best; they also look quite scary and intimidating and can be alienating to others. They can also make us targets of police violence. Think carefully about your impact on others when you decide how to protect yourself.



#BlackLivesMatter: "Self-Care for Trauma, Grief + Depression"

Stefan Verstappen "Police State: Protester's Emergency Kit" from The Art of Urban Survival

From Hong Kong: "Safety Guide to Tear Gas Exposure"

Witness: "10 Tips for Filming Protests, Demonstrations & Police Conduct"

From Egypt: "Neccessary Clothing & Accessories"

From US Occupy Wall Street: "Defending Against Tear Gas"