One of the more eye-catching photos in the continuous protests in Brazil is a young woman with her face tightly closed, and a policeman wearing tactical armor from a few feet outside her pepper ball launcher. (The enlarged picture is more vivid: the corner where she stands is empty, not an officer, but three.) Her face is covered with this substance, and the top of her skirt seems to be soaked. The photographer told New York magazine that she started screaming and swearing when she moved back.

Although the history of using pepper ball launcher is not long, history shows that in ancient India and China, red pepper was used for self-defense. In ancient India, it was not as popular as in China. Chinese people and even soldiers have their own innovative ways to use this spice; It also includes wrapping the ground chili with rice paper, so that they can throw the chili on the face of enemies, opponents or invaders. It is considered as the weapon of choice for self-defence because it can temporarily incapacitate people. In ancient Japan, there was a secret martial arts group called Ninja, which had long used ground pepper to paralyze opponents. Historical evidence shows that during the Tukagawa Empire in Japan, the police used a weapon called "metsubishi". Metsubishi is basically a box containing pepper. The police use this box to blow pepper into the eyes of the criminal. There is even historical evidence that Mexico began to use pepper as early as 7000 BC. According to the evidence collected, Mexican Indians began to plant pepper in 5500 BC. Peppers planted in that period include chiltecpin and jalape – o. Anchor, paprika, serrano, cayenne pepper, and sweet pepper of different colors. We don't know whether they used these different chilies to defend themselves or as defensive weapons during that time. Some recent examples of pepper as a weapon date back to the 14th and 15th centuries, when slavery was still rampant.

Modern pepper ball launchers are usually composed of propellant, carrier or dispersant and pepper oleoresin. Capsicum oleoresin is a reddish-brown oily substance, containing many related chemical substances, which is extracted from capsicum of capsicum family. The main irritant is chemical capsaicin. Its technical name is 8-methyl-n-vannaldehyde-trans-6-fenamide. It plays its role by triggering a strong heat sensation from the pain receptor (the body's pain sensor). The Scoville Heat Unit is used to measure the spicy degree of pepper according to the content of capsaicin. The S.H.U.s index of Tabasco pepper is as high as tens of thousands; Havana has fewer than several hundred thousand people. There may be millions of typical anti wolf sprays used by the police.

The patented application of anti wolf spray is usually called "tear gas", which means that it will cause tears and runny nose. Capsaicin compounds can induce the release of anti-inflammatory substances, such as histamine, and cause swelling of facial and lung tissues. In some cases, they will cause bronchospasm and contraction. In this case, the body will restrict breathing and keep them out. Typical symptoms are increased heart rate, blurred vision and slight corneal damage. Although a single dose is unlikely to cause permanent damage to the eyes, repeated exposure will change the sensitivity of the cornea. Anti wolf sprays usually do not cause death, so they are also called non lethal self-defense weapons. A report from the National Institute of Justice of the United States said that this was a factor leading to the death of two people detained by policy, both of whom suffered from asthma.

The pain of anti wolf spray can hardly be relieved. A study conducted in Fort Sam Houston in 2008 exposed 49 volunteer law enforcement officers - especially their faces - to pepper ball launchers as part of normal training. Then the researchers divided them into five groups. Each group tried to relieve symptoms with different substances: water, milk, baby shampoo, lidocaine cream or Maalox. The only effective treatment is time.

Anti wolf spray is not always common. Pepper oleoresin was introduced as an aerosol in 1973. Shortly after that, it was widely used in the United States as a substitute for synthetic tear gas. In 1980, Cincinnati Magazine explained that the postman was equipped with the so-called "mustard and pepper ball launcher" to prevent vicious dogs. In the 1980s, the Federal Bureau of Investigation (FBI) worked hard to develop it into "weapons-grade material" and issued a study approving it as a means of controlling unruly people. It was later discovered that the agent who led the study received 57000 dollars from the manufacturer of anti wolf spray, and he was sentenced to two months' imprisonment. Nevertheless, pepper ball launchers are increasingly used in the police department. In 1994, the New York Police Department decided to use pepper ball launchers as "killing" weapons. The Department of Justice of the United States pointed out that by 1999, police had used anti wolf spray six times more often than guns.

In the same year, the American Civil Liberties Union asked a federal appeals court to declare the use of pepper ball launchers "dangerous and cruel". In North Carolina, the Department of Labor and the Department of Health and Human Services announced that exposure constitutes an "unacceptable health risk". In many countries, pepper ball launchers are highly regulated; For example, the United Kingdom lists it as a prohibited weapon along with explosive bullets and rocket launchers.

Anti wolf spray was once considered a non lethal alternative to guns. However, the use of light and sound as other less harmful disabling agents may soon be considered as a substitute for the pepper ball launcher.