Quit the tear gas, doctors tell cops. It might exacerbate the pandemic

Using tear gas or other chemical irritants can worsen the risk of Covid-19 spreading through a crowd, according to a petition signed by more than 2,000 health professionals.

The minutes of violent coughing, sneezing, and face rubbing that the gases prompt people to do can help virus droplets infect healthy bystanders.

The petition for an anti-racist response to demonstrations going on nationwide was organized by doctors at the University of Washington. It calls for police to stop using any chemical irritants such as tear gas, smoke bombs, or pepper spray.

“Exposure to chemical irritants certainly makes the airways more susceptible to infection,” petition organizer and infectious disease physician Rachel Bender Ignacio said. “If people are coughing from any of these chemical irritants, then that increases their risk of spreading [Covid-19] to fellow protesters and to law enforcement as well.”

The symptoms of tear gas exposure are intense but, for the most part, brief.

“Coughing, increased mucous secretion, severe headaches, dizziness, dyspnoea, tightness of the chest, difficulty breathing, skin reactions, and excessive salivation are common,” a review in the journal The BMJ states.

Symptoms tend to fade away in half an hour or less, usually after a lot of sneezing, crying and violent coughing.

“That's probably the worst thing you want to do from a viral transmission perspective, because by coughing, you'll be projecting the viral droplets or the droplets containing virus much further,” infectious disease specialist Peter Chin-Hong of the University of California, San Francisco, said.

“You're going to be touching your face, and you'll be wiping your eyes and you'll be moving all that stuff around,” said Chin-Hong, who helped write the petition. “And that's a fertile ground for [Covid-19] transmission.”

An unnamed Seattle Police Department spokesperson declined to identify the types of tear gas and pepper spray that its officers use. The spokesperson emailed that the department's subject matter experts “are currently unavailable dealing with the on-going demonstrations.”

Racism and risk

Any gathering of hundreds of people presents a disease-transmission risk, even without exposure to tear gas or the risk of getting crammed into a police van or jail cell close to other people.

Photos of this week’s protests in Seattle have showed many participants wearing cloth face masks, which health officials have said should help reduce the risk of disease spread. Holding protests outdoors, where circulating air can help dilute viral loads, also lowers the risk.

Yet health officials have also emphasized that homemade masks are no substitute for social distancing.

“These masks are not tight-fitting like a medical personnel might wear, like an N-95 mask that reduces transmission of more droplets,” University of Washington pulmonologist Cora Sack said.

Shouting and singing are powerful ways to propel virus-containing droplets into the air. Research in May from the National Institutes of Health found that one minute of loud speech generates more than 1,000 virus-containing droplets, which can stay aloft 8 minutes or more.

While many protesters this week have been chanting, “Black lives matter,” the organization of that name has urged its members to stay home and stay healthy.

“Last week, we cautioned our communities to not participate in protests due to Covid-19, which Black and other people of color are disproportionately impacted by,” Black Lives Matter Seattle-King County chair Ebony Miranda said Wednesday.

In King County, Pacific Islanders and Latinos are five times as likely, and Blacks nearly three times as likely, to get Covid-19 as Whites or Asians are, according to Public Health – Seattle & King County.

“This virus has ravaged our communities in a way that largely mirrors the existing inequities and structural racism inherent in our healthcare systems,” Black Lives Matter Seattle-King County board member Marlon Brown said. “We refuse to encourage our community members to needlessly risk their lives and their health.”

Some public health experts say cities with large protests could see large coronavirus outbreaks in the weeks ahead.

“I'm very concerned that people who are in tight circumstances or were packed in together who are then coughing could absolutely spread the disease,” Harborview Medical Center emergency room physician Steve Mitchell said.

“There is still a virus in our community,” he said. “And we absolutely have to maintain social distancing and wearing masks and doing the things that keep all of us safe.”

The petition-signers, as well as public health agencies, say they support the demonstrations condemning police violence.

Gatherings are still prohibited in King County under Washington Gov. Jay Inslee’s Covid-19 emergency proclamation.

On Wednesday, the county applied for permission to begin reopening its economy, including allowing outdoor gatherings of up to five people from outside any one household.

Still, health officials praised and thanked protesters for gathering in much larger, riskier demonstrations to overturn systemic racism.

“Racism is a public health threat we can’t ignore. Nor can we wait until the pandemic is over to address it,” a blog post from the Washington Department of Health said.

“We continue to support demonstrators who are tackling the paramount public health problem of pervasive racism,” the health professionals’ petition states.

Chin-Hong had these suggestions to reduce the harmful impacts of demonstrations:

Protesters:

• Wear a mask
• Social distance whenever possible
• Bring extra masks and hand sanitizer for others
• Try to stay in the same cohort of people rather than mixing freely through an entire crowd

Police:

• Wear a mask
• Question people outdoors rather than indoors
• Avoid arresting people or putting them in confined spaces like police vans or jails
• Keep distance from protesters whenever possible
• Don’t use tear gas or other lung irritants

“It's likely that we may see an increase in cases due to protests with large numbers of people gathering, even if it's in the most socially responsible and socially distant way possible,” Sack said.

She said if coronavirus cases do spike in the weeks ahead, it would be difficult to tease out how much was due to protest gatherings and how much to changing public behavior as counties and states move toward reopening their economies.