What happened after US police teargassed protesters – a visual investigation | Portland | The Guardian

On 2 June 2020, residents of Portland, Oregon, took to the streets of downtown to protest the murder of George Floyd.

To break up the crowds, the Portland police bureau repeatedly deployed teargas.

The teargas use was indiscriminate, but the volumes of toxic chemicals unleashed in the community were long unknown.

Now, the scale of the contamination has been uncovered.

A groundbreaking analysis reveals how Portland, Oregon, was blanketed with toxic chemicals, raising concerns about global teargas use: ‘This was a disaster’

Video: Forensic Architecture, Alex Milan Tracy

visual investigation by Forensic Architecture

Investigators have created a 3D simulation of the Portland police bureau’s (PPB) extraordinary use of teargas during a major protest event on 2 June 2020.

Forensic Architecture (FA), a research agency that investigates human rights violations, worked with weapons experts to analyze hundreds of videos from that evening, along with internal police files, invoice records, manufacturer data and photos of teargas canisters. The analysis reveals that the city’s downtown was blanketed with gas at more than 50 times the level federal regulators consider “immediately dangerous to life or health”.

The findings, about the day local activists called Teargas Tuesday, forcefully contradict the department’s assertions in internal reports at the time, in which officers defended their “heroic actions”, saying police showed “extreme restraint”, “observed no injuries” from the spraying and used teargas to target specific individuals.

The model is the first of its kind to calculate the chemical concentrations in the air and deposits on the ground during a major teargas event in the US. It builds on existing reports and litigation alleging the months-long teargas use during the summer of protests caused severe injuries, long-term health problems, menstrual irregularities and environmental hazards.

The research renews pressure on the scandal-ridden police department and raises significant public health and civil rights concerns at a time when law enforcement agencies in the US and across the globe are escalating their use of teargas on crowds, including against protesters for abortion rights and police accountability.

“Teargas is a form of violence that is formless and shapeless and to a certain extent invisible,” said Lola Conte, an advanced researcher with FA, which is based at Goldsmiths, University of London. “Visualizing allows us to understand the massive scale of the spread, and I hope this makes the harm unignorable and shows that something is failing on so many levels with the use of teargas.”


PPB widely deployed a type of teargas known as CS, which can irritate the eyes, skin and respiratory system and cause disturbed cardiac rhythm and convulsions.

Forensic Architecture (FA) mapped the locations of 138 chemical munitions used across 25 blocks over 3.5 hours while also simulating that evening’s weather.

Researchers tracked how CS particles spread to estimate the concentrations protesters faced.

FA sampled 15 locations. Many exceeded an airborne concentration of 100 mg/m3 of CS, well above the 2 mg/m3 limit federal regulators consider “immediately dangerous to life or health”.

The simulation estimated ground-level deposits of CS particles, finding that the chemicals likely spread at least half a mile across downtown.

The highest recorded airborne concentration was roughly 4,500 mg/m3, more than 2,000 times the federal limit.

"There was an intense burning of my eyes and face,” recalled Jacinda Padilla, who was supporting protesters that week by handing out water, phone chargers and other supplies. They captured footage of the smoke plumes at 10.12pm, as explosions are heard in the background.

The teargas reached the nearby Willamette River, potentially polluting surrounding farmland and multiple wildlife refuges.

Portland officers indiscriminately sprayed teargas despite its own policies, which direct officers to consider proximity to schools, hospitals, freeways and other facilities and “minimize exposure to non-target persons”.

In subsequent reports, officers listed teargas as a “de-escalation technique” and wrote: “All of the officers and their actions should be commended for their heroic actions in protecting the city.”

The PPB declined the Guardian’s interview request, and did not answer questions about Forensic Architecture’s findings. PPB spokesperson Terri Wallo Strauss said in an email that the bureau in January updated its crowd control policy to make clear its “goal of avoiding the use of force, when feasible”, stating that officers “are only authorized to use objectively reasonable force based on the totality of the circumstances when no objectively reasonable and effective alternative presently exists”.

Strauss added that after George Floyd’s murder, Portland “experienced both peaceful protests and near daily occurrences of civil unrest, destruction and violence”, and that the bureau’s 170-day response was unprecedented in the city’s history. She also noted that PPB no longer has a “rapid response team”, which had previously handled protests and come under intense scrutiny, and that its annual training for officers includes updates on crowd control policy changes.

Cody Bowman, a spokesperson for Portland mayor Ted Wheeler, said his office looked forward to reviewing FA's research. He noted that Wheeler on 6 June 2020 had ordered police to only use CS in the event of a “serious and immediate threat to life safety, and there is no other viable alternative for dispersal".

‘A weapon of war’

Protesters in at least 100 US cities were met with teargas attacks in 2020, and in the three years since, law enforcement agencies have continued to deploy the chemical munition against crowds. In just the last year, police agencies have teargassed abortion rights and police violence protesters in Ohio, Georgia, and Arizona; used CS to break up a party in North Carolina; thrown a teargas grenade into a New Mexico home, causing a fire that killed a teenager; and badly damaged a residential property in Alaska with teargas deployments, with tenants throughout the building forced to deal with the damage and health harms. At the same time, lawmakers have been rolling back police reforms that were adopted in 2020, in some cases, loosening restrictions on when officers can use force.

Advocates have increasingly pointed out that teargas was a tool created in the first world war and later banned as a “weapon of warfare”, but that the Chemical Weapons Convention convened by the UN has said it can be used for “domestic riot control purposes”.

Even after the 2020 reckoning, in most cities, teargas remains stockpiled, its use widely permitted.

“If teargas is a war crime among soldiers, why is it appropriate to use on your own people?” said Juan Chavez, civil rights project director at the Oregon Justice Resource Center. “And the Portland police department doesn’t care about the effects of long-term consistent exposure to teargas. To them, it’s an inventory issue: ‘Do we have enough teargas and how much more can we use?’”

Every location analyzed had levels of CS teargas considered highly dangerous

Forensic Architecture simulated the airborne concentration of CS at 15 locations from the Portland protests


CS teargas


This sample’s CS level

was over 2,000 times

above the federal limit

4,000 mg per

cubic meter







on a log



Level considered (2mg/m3)

immediately dangerous*


Guardian graphic. Source: Forensic Architecture. *Note: 2mg/m3 is limit federal regulators consider “immediately dangerous to life or health”.

Forensic Architecture’s findings exposed how US regulations and police oversight mechanisms are fundamentally failing to prevent dangerous exposures, said Jasper Humpert, an FA assistant researcher: “The Portland police bureau acts as a body that constantly evades accountability. PPB doesn’t even have any form of assessment of the concentrations they expose people to.”

FA researchers reviewed internal records suggesting PPB knew that the Occupational Safety and Health Administration (Osha) deemed 2mg/m³ to be the threshold for dangerous exposure, but nonetheless did not track how much it was spraying and deployed dramatically higher amounts – in one area 2,000 times greater.

“It’s disturbing that this is so much higher than the standard, and yet it’s completely normal for protests everywhere,” said Dr Rohini Haar, an emergency medicine physician and adviser for Physicians for Human Rights (PHR). Haar released a report last month finding that more than 119,000 people have been reported injured by teargas and other chemical irritants across the globe since 2015.

Despite PPB facing oversight from the federal government due to claims of unconstitutional use of force, the US justice department has found that the police department has violated its own policies, and a judge found the city in contempt of his order to limit the use of teargas.

The teargas use was just one in a long list of recent PPB scandals: training documents uncovered last year included a meme celebrating violence against protesters; the police union leaked a false story in 2021 accusing the first Black woman city commissioner of being a suspect in a crime; a lieutenant was found to have exchanged friendly texts with a rightwing leader in 2017, but was cleared of wrongdoing; and the agency has faced scrutiny over its surveillance tactics, use of force and record of racial profiling.

But efforts to hold PPB accountable for the teargas use have had mixed success.

‘My whole body changed’

A key obstacle holding PPB liable for teargas injuries is that the impacts of prolonged exposure to teargas extended far beyond the immediate assault on their respiratory systems, advocates said.

Alex Johnson, 31, who regularly attended the protests, said at one of the nights in early June, she was hit with teargas as well as fragments of the canister thrown by police: “It’s the worst feeling in the world – like the inside of your eyes are on fire and being sandpapered at the same time.” As the days went on, however, she began to notice abnormalities in her menstrual cycle – after being heavily teargassed, she would get her period the next day.

“I started doubling over with cramps that I had never experienced before, and I’d have to go home and lay in my bed,” said Liv Vasquez, 42, who did not directly attend the protests, but lived near the site of the teargas releases, and in June often kept her window open, not knowing the chemicals could seep into her home and threaten her health. She also began experiencing spotting and asthma complications and breathing problems, she said.

Later that summer, she moved 10 miles away from downtown and quickly noticed improvements with her menstrual issues and respiratory system: “There was a burning while I was breathing that was gone once I moved.” She and Johnson both later sued the city over their teargas exposure.

“I feel like my whole body changed,” added Padilla, who volunteers with advocacy group Don’t Shoot Portland, which sued the city; they also reported heavy bleeding and pain, and said they developed eye problems after repeated teargas exposure.

Watch Forensic Architecture's full investigation

Video: Forensic Architecture

Vasquez said it was especially terrifying to see police teargas reproductive justice protests, given the concerns that exposure can potentially cause abortion or miscarriage, which in some states can lead to criminalization and arrest: “Knowing the aftermath of being teargassed, it’s like watching a car crash you’ve already been through.”

Experts say there is a lack of good data and research on the long-term impacts of teargas exposure, and a range of theories on how the chemical could be impacting menstrual cycles, with some noting that stress, trauma and dehydration at protests could also play a role. Vasquez’s lawyer ultimately withdrew her case, saying the lack of established research was a challenge in court.

The city of Portland in November settled Don’t Shoot Portland’s lawsuit and agreed to restrict its use of teargas and pay settlements to five demonstrators. The injunction requires the city to follow a new state law that restricts teargas use for crowd control, but the law contains significant exceptions, including permitting the chemical deployment to “bring an objectively dangerous and unlawful situation safely and effectively under control”.

Johnson, one of the plaintiffs, said it was a step in the right direction, but said she was disappointed that teargas is still allowed in some circumstances: “They’re saying they’ll follow the rules already in place.”

Bowman, the mayor's spokesperson, did not say whether the mayor would support a complete ban on teargas, but said in an email: "These unprecedented events characterize one of the most difficult chapters in our city's history, and I believe we have taken what we learned to move Portland forward in many positive ways and will continue to do so."

Lingering scars

Nearly three years after the teargassing began, the wounds from the events linger in the city of Portland, advocates said. Dr Brianna da Silva Bhatia, a Portland-based health strategist with Physicians for Human Rights, which investigated PPB’s use of force, said she remained worried that there were so few resources to help people deal with the medical and psychological toll of the events: “There was a lot of emotional, physical and mental trauma from that summer … This was a disaster that fractured the community, and accountability would be law enforcement owning that.”

Teressa Raiford, executive director of Don’t Shoot, said she suffers PTSD from that summer and that true justice would be a total ban on teargas and other chemical weapons – and an end to the police abuse that demonstrators were calling for when they first took to the streets.

“I hope at some point we as a society can see there isn’t a need for this type of policing that allows for this violence to happen to people, and that we dismantle it,” she said. “The fact that they used this level of violence to suppress people’s voices and deflect the communication of protesters, that’s never going away. We can never fix that. And I’ll never feel safe around the police or want to negotiate safety with them, because their intent to harm us was just so brazen.”

FA’s research will be featured in an exhibition on policing and its local histories at the Portland Institute of Contemporary Art from February to May 2024.