Why 1,200 health experts are urging cops to stop using this "horrifying weapon"

What you hear first is the pop of deployed flash-bang grenades and the clang of canisters hitting the pavement. A cloud of white powder unfurls, sparking widespread panic through crowds.

When tear gas hits the body, the potent substance infiltrates the eyes, nose, throat, and skin, plunging the attacked into pain. It causes uncontrollable coughing and intense burning sensations. It can become extremely difficult to breathe or see clearly. After the acute, disabling effects subside, tear gas can also cause lasting lung and eye damage, as well as enduring psychological trauma.

"Imagine eating a chili pepper, but that experience is not just happening in your mouth — it is happening on every area of exposed skin," Danielle Guldin, a former nuclear, biological, and chemical defense specialist in the US Marine Corps, tells Inverse. The burning and tingling sensation can feel up to 100,000 times stronger than the sting of wasabi.

Tear gas, prohibited in war since 1993, has become a fixture of American protests. On June 1, a group of peaceful protesters was cleared from Lafayette Square with tear gas for President Donald Trump to take photos at a nearby church. Similar scenarios have played out in cities like Charlotte, Los Angeles, and San Antonio. In Philadelphia, police deployed tear gas on demonstrators trapped on a hillside. The City of Columbus is currently investigating the death of a student after they were exposed to tear gas during a protest.

On June 2, 1,288 medical and public health professionals called for police to stop using "any use of tear gas, smoke, or other respiratory irritants, which could increase the risk for Covid-19 by making the respiratory tract more susceptible to infection, exacerbating existing inflammation, and inducing coughing" in an open letter.

Experts who spoke with Inverse agree, describing tear gas as counterproductive, unethical, and ultimately dangerous. It's time to stop using it for crowd control, they say.

"It is abhorrent, appalling, disgraceful," Ranit Mishori, a family physician and professor at Georgetown University School of Medicine, tells Inverse. Mishori is also a senior medical advisor at Physicians for Human Rights, a United States-based nonprofit organization that uses medicine and science to document and advocate against mass atrocities and severe human rights violations around the world.

"This is a disproportionate and excessive use of force on otherwise peaceful demonstrators who have the right to assemble the right to demonstrate."

Kelsey Davenport is the director for nonproliferation policy at the Arms Control Association, a nonpartisan organization dedicated to promoting public understanding of and support for effective arms control policies. She tells Inverse "tear gas is banned in warfare for a reason."

"If the United States is committed to banning it on the battlefield, we should ban it on our streets as well."

What is tear gas?

Tear gas, pepper spray, and mace are composed of a class of chemical compounds designed to activate pain receptors and "temporarily make people unable to function by causing irritation to the eyes, mouth, throat, lungs, and skin." Most law enforcement agencies in the United States use a chemical called chlorobenzylidene malononitrile (CS).

CS is packed into tear gas grenades, aerosol canisters, and pellets that are launched into the air or sprayed at point-blank range. When fired into crowds, projectiles can hit demonstrators with tremendous force — potentially injuring people’s eyes, head, and upper and lower extremities.

Tear gas invades the body's mucous membranes — the eyes, nose, mouth, skin — causing severe irritation, inflammation, and pain, as well as a running nose and tearing eyes. It can trigger uncontrollable coughing, choking, chest tightness, and temporarily blind those exposed.

Often, these painful effects subside within 15 to 30 minutes after breathing fresh air and cleaning affected areas. Still, the health effects of tear gas aren't always temporary.

International case reports show extended exposure or high doses of tear gas can kill through respiratory failure, chemical burns, or death by projectile force — especially in confined spaces.

Some scientists caution tear gas use in instances of "large‐scale civil disorder" could result in extended, repeated, or highly concentrated exposures, which would pose a greater threat to respiratory health.

"Using tear gas for peaceful protest is both inhumane and irresponsible; inhumane in that tear gas is a chemical weapon that has been banned abroad, and yet we're using it at home," Ayesha Appa, a chief fellow of infectious diseases at the University of California, San Francisco, tells Inverse.

Appa finds it particularly inhumane that tear gas can cause bronchospasms, a tightening of the muscles of the airways in the lungs, which makes breathing difficult. This can be particularly harmful and damaging for those who have asthma or other underlying lung problems.

"We know due to structural racism, Black Americans face higher rates of asthma. It feels not only acutely cruel in the context of Covid-19, but is yet another layer of structural racism being perpetuated through the use of tear gas on a population that may be particularly vulnerable to its effects," Appa says.

Appa worries the substance may heighten transmission of Covid-19 since tear gas causes coughing and sneezing fits, as well as droplet production.

The long-term effects of tear gas — While law enforcement agencies deem tear gas a safe riot control agent, scientists argue otherwise. This is because the research used to support its use is drawn from studies on rodents and small groups of previously healthy people in controlled conditions. These studies are considered inadequate by scientists.

The largest studies have been done on military recruits exposed to tear gas during training exercises. In those studies, tear gas led to a higher risk of contracting influenza, pneumonia, bronchitis, and other respiratory illnesses.

"Sometimes these types of weapons for crowd control are called nonlethal," Mishori says. "I want to disabuse everyone from the notion that these are truly nonlethal. They are not benign weapons and they can cause a lot of harm."

Crucially, tear gas and pepper spray "do not discriminate" between people who are engaged in acts of violence and people who are protesting peacefully, Davenport stresses.

These chemical weapons can be carried by the wind, endangering anyone in the surrounding area. They can seep into surrounding buildings and homes. Currently, scientists don't know how potentially vulnerable populations like children, pregnant women, or the elderly fare when exposed to tear gas.

Being attacked by tear gas can also impact people psychologically, skyrocketing anxiety and distress.

"Being in the crowds, venting and expressing your disaffection with what is going on in the US and then being gassed or shot at, in close range sometimes, while being peaceful — that can be extremely traumatic," Mishori says.

A weapon of "last resort"— Tear gas, like all chemical weapons, was banned in international war by the Chemical Weapons Convention in 1993. (It was ratified in the US in 1997.) Domestically, tear gas is considered a "riot control agent," permitted by law enforcement use.

"There is a carve-out in the Chemical Weapons Convention that allows for certain agents like tear gas to be used for riot control purposes," Davenport, who is an expert on arms proliferation, explains. "But we've seen time and time again that the United States is not using tear gas to control riots. It is using tear gas to punish protesters and disperse crowds, and that is unconscionable."

Guldin, the ex-Marine and chemical weapon expert, says this particular tactic and lots of other weapons are inappropriately being used against people counter to the way they were designed.

"The power of this particular weapon is being severely abused against people whose actions are not worthy of such force," Guldin says. "It’s really, really messed up and awful that those weapons that are outlawed abroad are now turned on US citizens who are exercising their right to free speech and protest.”

Mishori argues that given the potential harm they can cause, tear gas should "be a weapon of last resort."

"It is a violation of human rights to attack peaceful assemblies, peaceful demonstrators, and unarmed demonstrators. It is extremely wrong and should be banned to use them in this context," Mishori says.

When used in the place of physical force from impact weapons or firearms, less-lethal weapons like pepper spray can reduce injury risk for law enforcement officers and demonstrators, some researchers say.

However, other research dating back to the 1960s suggests tear gas, other weapons, and riot control agents often backfire, creating the violence they aim to prevent.

In a crowd, tear gas deployment can spark widespread panic, confusion, stampedes, and trampling that lead to further injury and be "completely counterproductive," Mishori and Appa say.

"When the police employ tear gas, it creates chaos," Davenport agrees. "It creates fear, and that seems to only inflame situations further. It does not seem to be effective in terms of maintaining calm and nonviolent situations."

Sociologists and some veteran leaders of police argue that de-escalation techniques like negotiation, transparent communication, and empathy can avoid this potentially dangerous feedback loop.

"The harm is compounded by its misuse," Mishori says. "Sometimes you think to yourself: Is it really misuse? Or is it used intentionally to intimidate or retaliate against people and instill fear in them — as a means of scaring them and preventing them from demonstrating as opposed to purely dispersing them?"