Last July, Indigo Namkoong stood in Lownsdale Square in Portland, watching canisters of tear gas arch over a crowd that had converged outside the city’s Justice Center. People had come from all over the city to rally against violent and racist policing and the percentage of the city’s budget that was handed over to the police department every year.

Portland wasn’t the only place where this was happening. In cities across the United States, a wave of grassroots protest arose after the murder, in Minneapolis, of George Floyd by a group of police officers—Derek Chauvin, who knelt on Floyd’s neck until he stopped breathing, and three other officers who helped Chauvin and held back the crowd begging Chauvin to stop. The sheer awfulness of Floyd’s death inspired thousands of people who had never thought much about the police before to attend local protests calling for police reform. 

In many of those cities, tear gas was the response. In Washington, DC, police officers and US park police used tear gas to clear protesters from Lafayette Square so that then-president Trump could pose in front of a church with a Bible. In Philadelphia, police repeatedly tear-gassed peaceful marchers. In Denver, police gassed medics. No city was tear-gassed as much as Portland, where observers counted gas being deployed more than 20 times in a single night. 

When Namkoong arrived in Lownsdale Square, she and the rest of the crowd had come prepared. People around her wore respirators and goggles and carried umbrellas to keep the tear gas from directly raining down on their faces and leaf blowers to disperse any gas away from the crowd. But that night in July, as Namkoong stood holding up her umbrella, the tear gas canisters kept coming to the point where she could barely see 10 feet in front of her. Her respirator stopped working, and it felt like her lungs were on fire.

The day after she was gassed, Namkoong wrote in a court filing, she woke up feeling like she had the worst hangover of her life. She couldn’t think clearly. She had no history of asthma, but for weeks afterward, she felt weak and short of breath sometimes, and struggled to walk uphill.

Even people who avoided the Justice Center at times when police were using tear gas felt its effects. “My 11-year-old son was in Chapman Square with my partner in the early evening,” wrote Brenna Bell, an environmental attorney, as part of the same court filing. “When he came home he told me he had been tear-gassed. I was incredulous because they were home before the time federal agents typically shot gas at the crowd. When I pressed for more details, my son told me he had been ‘tear-gassed by the ground’: When he had sat down on the grass in Chapman Square, it released a puff of chemicals into the air so strong he had to immediately stand up and move away.”  

A few days later, Bell was standing under a grove of trees in front of the Federal Courthouse when a gust of wind blew through, rustling the tree leaves. “I immediately felt my eyes burn and had a hard time breathing,” Bell wrote. “As the federal agents had not yet deployed any tear gas that evening, I believe the gas accumulated on the leaves of the trees and caused this irritation as it blew off.”

“Such a device, I believe, would work to perfection”

Before tear gas was even on the market, police departments wanted it. 

“I am writing to you on the subject of the use of tear gases in connection with crowds of strikers and disorderly persons in the street during the time of riot or other such disturbances,” wrote A.D. Porter of the New York Police Department, to the director of the US Chemical Warfare Service (CWS) in 1919. “It has occurred to me that these gases might be an efficient agency in suppressing disorder.” 

A few months later, another letter arrived at the CWS, from the Department of Public Safety in Norfolk, asking for some of the tear gas grenades still under development at Edgewood Arsenal in Maryland. “In this city,” it read, “where it is possible that we may have a great deal of trouble with the negro element, such a device, I believe, would work to perfection.” The CWS was eager to transform what was then a military weapon into a tool of federal and local law enforcement, but the US War Department refused to approve its use within US borders (colonies like the Philippines were another story). 

The War Department’s resolve to not use tear gas domestically lasted until 1932. On order of Herbert Hoover, federal troops used tanks and tear gas grenades to clear out tent cities built by the Bonus Army—several thousand military veterans and their families who had marched to Washington in hopes of getting federal aid during the Great Depression. Hoover, already unpopular, became even less so and lost the next election to Franklin Delano Roosevelt. When the military veterans returned, the Roosevelts fed them, provided tents, joined a singalong at the protest site, and offered them jobs with the Works Progress Administration. Most accepted those terms and returned home. 

In the 1990s, the international Chemical Weapons Convention banned the use of tear gas in war but reserved the right for individual countries to use it within their own countries. The US is one of several countries that have gone on to act in ways that appear to violate the terms of that agreement, by doing things like firing tear gas across the Mexican border at people—including children—attempting to claim asylum.

Who called in the Feds?

The officers using the tear gas outside the Justice Center weren’t all from Portland. Earlier in July, people began to notice law enforcement personnel in unfamiliar uniforms around the city. A court filing revealed that the officers had been sent by the Department of Homeland Security as part of something called Operation Diligent Valor. Diligent Valor described itself as a mission to protect federal buildings, but it behaved more like a military occupation and brought a seemingly endless supply of tear gas, which it continued to use even after the mayor of Portland ordered local police to stop tear-gassing protesters in the middle of a pandemic, and in the early months of fire season.

No one could—except for DHS—be exactly sure what it was firing into the crowd, and if all of it was even tear gas, let alone what kind. CS gas is the most common; CN is less frequently used because of its higher risk of killing people. CR gas, also less used, is very difficult to get off of skin and can linger on some surfaces for over a month. OC gas (a.k.a. pepper spray) causes fewer allergic reactions but is also hard to remove and can cause corneal damage if it gets into your eyes. Newer formulations, like CS2 and CSX, are similar to CS gas but don’t evaporate as quickly.

Some witnesses resorted to gathering empty canisters in the streets for clues. This revealed which brands were being used (and that many canisters were expired) but didn’t provide enough of a trail to show just how much was being used and when. Public records requests to Portland police revealed some information, but those made to DHS have still gone unanswered.

The closest thing to those answers may lie in the first environmental law ever written in the United States and the work of a small group of local environmental lawyers—and their allies—who realized that what looked on the surface like a civil liberties issue was also an environmental one.

The science of tear gas is the science of healthy young men

Most of the data that concluded that tear gas was safe to use was collected between the 1950s and '70s, said Sven Eric Jordt, a professor of anesthesiology at Duke University whose research focuses on the ability to feel touch, pain, and irritation. That research was done by the two groups most interested in using tear gas: police departments and the military. The research was done on the population that was easiest for both agencies to experiment on: new recruits.

One limitation of these research practices is that the gases were only tested on people who were young, fit, male, and healthy enough to pass a military or police physical. “So what happens to a diverse population of protesters that are young, that are old, and may have an underlying condition?” said Jordt. The kind of research that would truly break new ground—like going to a protest and measuring how concentrated the gas was, or tracking people at a protest who had been exposed over a period of several weeks—even months—was not happening. “There’s really a vacuum there of oversight and regulation and research at this time."

Meanwhile, more recent research challenges the idea that even healthy young men can be tear-gassed with impunity. Studies of army recruits in the 2010s found an increase in visits to the infirmary for acute respiratory illness among recruits during weeks four through six of Basic Combat Training—right after an exercise called Mask Confidence Training, where recruits in gas masks walk into a room filled with CS gas, perform exercises, then take off the masks and find their way out of the room. The reaction of the recruits to the gas was violent: They cried and coughed helplessly, and often vomited—but the assumption before that had been that any harm was short-lived. After the concentration of CS gas was reduced to a 10th of its former strength, infirmary visits declined, though not completely.

What is clear is that tear gas has effects on the respiratory system that can become more chronic over time, and that it can trigger allergic reactions like dermatitis and asthma. How long those effects last, though, remains to be known. In some cases, said Jordt, researchers could only collect anecdotal data from surveys of people who were at protests or lived nearby. “In the Arab Spring, the doctors who were treating patients were actually persecuted. So there's really no scientific report from that time that is really solid and that would stand up to scrutiny from a peer-reviewed journal.” 

Several peer-reviewed studies done in Turkey around the same time, though, did show chronic respiratory effects, and a case study published in the Lancet documented the development of asthma and contact dermatitis in a photojournalist who had spent six weeks covering protests in Hong Kong.

In the 1980s, a review published in the Journal of the American Medical Association found that in areas where protesters in Seoul, South Korea, were tear-gassed, nearby shopkeepers and their children told interviewers that they experienced persistent coughing and shortness of breath for weeks after. In 2011, tear gas was briefly banned in Chile because of reports that it was causing miscarriages. Another study from 2014 found that in Turkey, people who attended protests where tear gas was used, or lived and worked nearby, were more likely to have shortness of breath and other respiratory problems compared with a control group, even months after exposure—symptoms that reminded the researchers of earlier studies of Iranian veterans who had been exposed to mustard gas.

A study published in May in BMC Public Health by Britta Torgrimson-Ojeri, a nurse in Portland, found that an overwhelming majority of protesters in Portland reported a wide range of symptoms—trouble breathing, stomach problems, strange rashes, headaches, hair loss, and unexpected heavy periods among them—in the days (and sometimes weeks) following being tear-gassed. But because the study was based on an internet survey, it’s still not ideal—an invitation to more research, rather than a conclusive document. 

In Portland, police and federal agents used so much tear gas that it coated sidewalks. In August 2020, the Portland Department of Environmental Services (DES) cleared six storm drains near the Justice Center to test what was in the sludge. They were denied access to a seventh storm drain, now located inside a fence that DHS had built around the courthouse.  

When the results were released a month later, Portland DES reported that it was difficult to tell which chemicals in the sludge came from tear gas and which came from all the other terrible things that normally collect in storm drains—but that the drains it had sampled showed elevated levels of barium, copper, lead, and zinc compared with a control storm drain far away from the protests. Since the components that make up tear gas are chlorinated, when they are released it’s possible that they form stable, dioxin-like compounds that could remain in the environment for decades or longer. 

“The major agencies that should look into this,” said Jordt, “like the CDC or EPA, they are not doing anything.”

The joke that got real

When the Trump administration sent the Department of Homeland Security to Portland to shoot tear gas and other chemical munitions like smoke bombs at protesters, a small group of environmental lawyers in Oregon—Nick Cady at Cascadia Wildland, Elisabeth Holmes at Willamette Riverkeeper, and Brenna Bell at BARK—began joking about whether, now that the Feds had gotten involved, NEPA (the National Environmental Policy Act) now applied. “It was a joke,” said Cady, “because it's this law that's despised by Republicans and Democrats alike” in the Capitol.

Signed into law by Richard Nixon in 1970, in the wake of the freeway revolts of the 1950s and '60s, NEPA demands that every federal agency tasked with making an important decision prepare a detailed statement on:

(1) the environmental impact of the proposed action; (2) any adverse effects that cannot be avoided; (3) alternatives to the proposed action; (4) the relationship between local short-term uses of man’s environment and the maintenance and enhancement of long-term productivity; and (5) any irreversible and irretrievable commitments of resources that would be involved in the proposed action.

NEPA had been used to block oil pipelines and to challenge oil and gas on public lands (when the federal government has failed to accurately describe and explain the environmental impacts of those projects). But NEPA has also been used to block renewable energy infrastructure like offshore wind (hence the dislike by certain environmentalists). The statute has been weakened over time by federal agencies and Supreme Court rulings authored by Justice Scalia. But NEPA remains a powerful tool for protecting human health and the environment—so much so that the Trump administration was in the process of trying to gut it.

NEPA was, traditionally, a tool that people used to ensure the Bureau of Land Management, or the Forest Service, or the EPA, did a better job of protecting the environment when those agencies were involved in federal projects. Using it to challenge the Department of Homeland Security is virtually unprecedented. “Most of the time I deal with NEPA, let's say for a timber sale, it could be because the Forest Service wants to cut down trees that are going to affect a fish or the spotted owl,” said Holmes. “Or, for example, if a federal agency is funding a factory expansion, they are funding an expansion into an area that's going to pollute the water.”

But NEPA can also be used, Holmes said, to protect people from federal actions that affect low-income and BIPOC communities. “One of the key things about this case,” said Holmes, “is the disregard that the Department of Homeland Security has given the public—most disturbingly in this case, because it's protesters advocating for racial justice. The fact that DHS is unwilling to do an environmental analysis before using tear gas and chemical munitions, in a situation where we've got Black and Indigenous people and people of color, protesting, and white people protesting, but over a racial issue, it's just a really horrible example of racial and environmental injustice.”

“We began digging around,” said Cady. “I had an awesome legal intern at the time, through Lewis and Clark Law School, and the legal violations quickly became clear.” It was definitely intimidating, Cady said, going after DHS, because the suit would require sworn statements from people who had been tear-gassed at Black Lives Matter protests. Some of these people were afraid of putting themselves out there before DHS and their lawyers, given how DHS had acted during the protests—particularly the way that agents had been using unmarked vans to follow (and in some cases, take in for interrogation) people that it believed were participating in the protests. Cady knew they needed experienced deposition lawyers to protect these declarants, so a friend from law school reached out to the ACLU about whether they would be willing to help with the NEPA case.  

“I got a call back,” said Cady. “That was just like, 'Hey, can you kind of jump on a quick call and just walk us through some of this again?' I'm in a hoodie, and I was like, 'It’s a Zoom meeting. Maybe I'll just throw on a collared shirt, just to be safe.'” And then we got on the meeting, and the ACLU’s national litigation committee was there.” The ACLU’s litigation committee unanimously voted to join the case.

If the case succeeds, DHS will be forced to go far beyond just providing information on what it used on protesters, said Holmes. It will have to do more than just speculate on what the possible effects of tear gas escaping into the Willamette River might be as well. “It's got to be a meaningful analysis. You can't just say something is an aquatic toxicant and then wash your hands of the rest of the situation. You have to ask, 'Is it toxic to fish? Is it an aquatic toxicant for people that are swimming in the water? What happens if you ingest a fish that has some of this in it?' There's more that needs to be done. And from what we can tell, that information and legally required analysis is not already in the public domain.” 

In every city across the United States where local police shot tear gas at protesters all summer, NEPA did not seem to apply—it was a local, not a federal matter. It seems almost too perfect that the Trump administration, by sending in a federal agency to tear-gas anti-racist protesters (quite possibly as a dog-whistle from the Trump administration to its white supremacist base) could leave the DHS wide open to an environmental lawsuit that would force DHS to do the first real scientific assessment of tear gas on human health and the environment.

“All we're asking for is for the government to conduct the environmental and human health review that they're supposed to do,” said Holmes. “And if we win, the judge will say, 'Yes, they violated NEPA by not doing that analysis. And they have to do it now.'”