Editing Chemical warfare (section)

===Chemical warfare agents===
{{See also|List of chemical warfare agents}}
The chemical used in warfare is called a ''chemical warfare agent'' (''CWA''). About 70 different chemicals have been used or stockpiled as chemical warfare agents during the 20th and 21st centuries. These agents may be in liquid, gas or solid form. Liquid agents that evaporate quickly are said to be ''volatile'' or have a ''high [[vapor pressure]]''. Many chemical agents are [[volatile organic compounds]] so they can be dispersed over a large region quickly.{{citation needed|date=March 2021}}<ref>{{Cite book|title=Gas Info|chapter=9.4 Effusion and Diffusion of Gases|chapter-url=https://opentextbc.ca/chemistry/chapter/9-4-effusion-and-diffusion-of-gases/|url-status=dead|website=BCcampus|year=2016|publisher=OpenStax|access-date=March 12, 2021|archive-date=December 4, 2021|archive-url=https://web.archive.org/web/20211204121104/https://opentextbc.ca/chemistry/chapter/9-4-effusion-and-diffusion-of-gases/}}</ref>

The earliest target of chemical warfare agent research was not toxicity, but development of agents that can affect a target through the skin and clothing, rendering protective [[WWI gas mask|gas mask]]s useless. In July 1917, the Germans employed [[sulfur mustard]]. Mustard agents easily penetrate leather and fabric to inflict painful burns on the skin.

Chemical warfare agents are divided into ''lethal'' and ''incapacitating'' categories. A substance is classified as incapacitating if less than 1/100 of the [[lethal dose]] causes incapacitation, e.g., through nausea or visual problems. The distinction between lethal and incapacitating substances is not fixed, but relies on a statistical average called the {{LD50}}.

====Persistency====
Chemical warfare agents can be classified according to their ''persistency'', a measure of the length of time that a chemical agent remains effective after dissemination. Chemical agents are classified as ''persistent'' or ''nonpersistent''.

Agents classified as ''nonpersistent'' lose effectiveness after only a few minutes or hours or even only a few seconds. Purely gaseous agents such as chlorine are nonpersistent, as are highly volatile agents such as sarin. Tactically, nonpersistent agents are very useful against targets that are to be taken over and controlled very quickly.

Apart from the agent used, the delivery mode is very important. To achieve a nonpersistent deployment, the agent is dispersed into very small droplets comparable with the mist produced by an aerosol can. In this form not only the gaseous part of the agent (around 50%) but also the fine aerosol can be inhaled or absorbed through pores in the skin.

Modern doctrine requires very high concentrations almost instantly in order to be effective (one breath should contain a lethal dose of the agent). To achieve this, the primary weapons used would be rocket artillery or bombs and large ballistic missiles with cluster warheads. The contamination in the target area is only low or not existent and after four hours sarin or similar agents are not detectable anymore.

By contrast, ''persistent'' agents tend to remain in the environment for as long as several weeks, complicating decontamination. Defense against persistent agents requires shielding for extended periods of time. Nonvolatile liquid agents, such as [[blister agent]]s and the oily [[VX (nerve agent)|VX]] nerve agent, do not easily evaporate into a gas, and therefore present primarily a contact hazard.

The droplet size used for persistent delivery goes up to 1&nbsp;mm increasing the falling speed and therefore about 80% of the deployed agent reaches the ground, resulting in heavy contamination. Deployment of persistent agents is intended to constrain enemy operations by denying access to contaminated areas.

Possible targets include enemy flank positions (averting possible counterattacks), artillery regiments, command posts or supply lines. Because it is not necessary to deliver large quantities of the agent in a short period of time, a wide variety of weapons systems can be used.

A special form of persistent agents are thickened agents. These comprise a common agent mixed with thickeners to provide gelatinous, sticky agents. Primary targets for this kind of use include airfields, due to the increased persistency and difficulty of decontaminating affected areas.

====Classes====
Chemical weapons are agents that come in four categories: [[Pulmonary agent|choking]], [[Vesicant|blister]], [[Blood agent|blood]] and [[Nerve agent|nerve]].<ref>Gray, Colin. (2007). ''Another Bloody Century: Future Warfare''. p. 269. Phoenix. {{ISBN|0-304-36734-6}}.</ref>  The agents are organized into several categories according to the manner in which they affect the human body. The names and number of categories varies slightly from source to source, but in general, types of chemical warfare agents are as follows:

{{Chemical warfare/CW table}}
There are other chemicals used militarily that are not scheduled by the CWC, and thus are not controlled under the CWC treaties. These include:
* [[Defoliant]]s and [[herbicide]]s that destroy vegetation, but are not immediately toxic or poisonous to human beings. Their use is classified as [[herbicidal warfare]]. Some batches of [[Agent Orange]], for instance, used by the British during the [[Malayan Emergency]] and the United States during the [[Vietnam War]], contained [[Polychlorinated dibenzodioxins|dioxins]] as manufacturing impurities. [[Dioxins and dioxin-like compounds|Dioxins]], rather than Agent Orange itself, have long-term cancer effects and for causing genetic damage leading to serious [[birth defects]].
* [[Incendiary device|Incendiary]] or [[Explosive material|explosive]] chemicals (such as [[napalm]], extensively used by the United States during the [[Korean War]] and the Vietnam War, or [[dynamite]]) because their destructive effects are primarily due to fire or explosive force, and not direct chemical action. Their use is classified as [[conventional warfare]].
* [[Virus]]es, [[bacteria]], or other organisms. Their use is classified as [[biological warfare]]. [[Toxin]]s produced by living organisms are considered chemical weapons, although the boundary is blurry. Toxins are covered by the [[Biological Weapons Convention]].

====Designations====
{{Further |chemical weapon designation}}

Most chemical weapons are assigned a one- to three-letter "[[NATO]] weapon designation" in addition to, or in place of, a common name. [[Binary chemical weapon|Binary munitions]], in which precursors for chemical warfare agents are automatically mixed in shell to produce the agent just prior to its use, are indicated by a "-2" following the agent's designation (for example, GB-2 and VX-2).

Some examples are given below:
{| style="margin:0 0 1em 1em; border:1px solid #aaa; background:#edf3fe;" cellpadding="5" cellspacing="0" cellpadding="5" cellspacing="0"
|-
! style="background:#ccf; border:1px solid #aaa; padding:0 5px;"| '''''Blood agents:'''''
! style="background:#ccf; border:1px solid #aaa; padding:0 5px;"| '''''Vesicants:'''''
|-
| style="border:1px solid #aaa;"|
* [[Cyanogen chloride]]: CK
* [[Hydrogen cyanide]]: AC
| style="border:1px solid #aaa;"|
* [[Lewisite]]: L
* [[Sulfur mustard]]: H, HD, HS, HT
|-
! style="background:#ccf; border:1px solid #aaa; padding:0 5px;"| '''''Pulmonary agents:'''''
! style="background:#ccf; border:1px solid #aaa; padding:0 5px;"| '''''Incapacitating agents:'''''
|-
| style="border:1px solid #aaa;"|
* [[Phosgene]]: CG
| style="border:1px solid #aaa;"|
* [[3-quinuclidinyl benzilate|Quinuclidinyl benzilate]]: BZ
|-
! style="background:#ccf; border:1px solid #aaa; padding:0 5px;"| '''''Lachrymatory agents:'''''
! style="background:#ccf; border:1px solid #aaa; padding:0 5px;"| '''''Nerve agents:'''''
|-
| style="border:1px solid #aaa;"|
* [[Pepper spray]]: OC
* [[Tear gas]]: CN, CS, CR
| style="border:1px solid #aaa;"|
* [[Sarin]]: GB
* [[VE (nerve agent)|VE]], [[VG (nerve agent)|VG]], [[VM (nerve agent)|VM]], [[VX (nerve agent)|VX]]
|}