Some weapons use bad air. 
Some weapons use bad air. 
These weapons were used in big wars. 
Leaders saw this was wrong. They made rules to stop it. They wanted to keep people safe.
Many lands joined a big group. 
Most countries now say these weapons are not allowed. People work hard to make the world better.
Chemical weapons use harmful chemicals to hurt or kill people. 
People have used these weapons for a long time. They were used in a big way during World War I. This caused many injuries and deaths. 
After the wars, many countries kept large stores of these weapons. This was part of the Cold War. In 1993, many nations signed a new rule. This rule is the Chemical Weapons Convention. 
Chemical weapons are special tools that use harmful substances to cause injury or death. 
These weapons work by using toxic properties to achieve a goal. They can be delivered in many ways. Some are released from aircraft or rockets. Others come from remote-controlled containers. Some chemicals are unitary, meaning they are used as they are. Other weapons are binary. This means two different chemicals combine right where they are used. Some agents are very volatile and spread quickly. Others, like VX, are persistent and stay in an area for a long time.
History shows that people have used chemical tools since ancient times. However, they were first used on a large scale during World War I. Many nations used mustard gas, chlorine, and phosgene gas. These gases caused blindness, lung scarring, and death. 
After the big wars, many countries kept large amounts of these weapons. During the Cold War, the Soviet Union and the United States had the largest stockpiles. They focused on chemicals like sarin and mustard for use in Europe. Later, chemical weapons were used in the Iran-Iraq War and the Syrian civil war. In 1993, the world created the Chemical Weapons Convention. This is a global rule that bans making, storing, and using these weapons. There are now 193 countries that follow this treaty. The United States finished destroying its own stockpile by 2023. 
Today, the world works hard to prevent the use of these substances. An organization called the OPCW helps manage the rules of the convention. While most countries follow the rules, some nations like North Korea have not joined. Small amounts of chemicals are still allowed for research and defense. This helps people learn how to protect themselves. People can use special equipment and training to stay safe. Understanding this history helps us see why these rules are so important for peace.
A chemical weapon is a specialized munition that uses toxic chemicals to cause death, injury, or incapacitation.
Chemical agents work through various biological and physical mechanisms. Lethal agents are categorized by how they affect the body. Nerve agents, such as tabun, sarin, soman, VX/VR, and Novichok, attack the nervous system. Blister agents, primarily mustard gas, cause severe skin and eye damage. There are also non-lethal agents, such as tear gases like CS gas or pepper spray. These are used for sensory irritation rather than death. Some agents are incapacitating, such as BZ. Chemicals can be unitary, meaning they are used in their pure form. Other weapons are binary. In binary weapons, two different precursors combine in situ, or on the spot, to create the active agent. Some chemicals are highly volatile and spread rapidly through the air. Others, such as VX, are persistent and remain in an environment for a long time.


Despite limited battlefield use in World War II, Nazi Germany used chemical agents for genocide. They used Zyklon B, a commercial hydrogen cyanide blood agent, in gas chambers. They also used carbon monoxide against various populations. The Holocaust resulted in the largest death toll from chemical weapons in history. In the post-war era, the Cold War saw massive stockpiling. The Soviet Union and the United States created the largest chemical weapon programs in history. They focused on sarin, VX/VR, and mustard gas for use in Europe. Later conflicts, such as the Iran-Iraq War and the Syrian civil war, saw repeated use of these weapons. In the Iran-Iraq War, approximately 100,000 Iranian troops became casualties of Iraqi chemical weapons.

While the treaty is widely followed, challenges remain. Some nations, such as Syria and Russia, are believed to have violated prohibitions on use and stockpiling. Israel and North Korea are not parties to the convention. Small research quantities are still permitted for CBRN defense purposes. This allows nations to develop proper protection, such as training and decontamination measures. Understanding these complex systems and historical patterns is essential for maintaining global security and preventing future harm.
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