NORTH TEXAS (CBDSFW.COM) – From Dallas and Fort Worth to Portland, Minneapolis and just outside the White House, tear gas has sent protesters scrambling with stinging eyes and burning skin over the past several weeks.

The chemical dates back to World War I when it was used by troops to drive enemies from the trenches.

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Since then, it has been used on American soil many times.

In 1932, police sprayed it when veterans marched on Washington.

In the 1960s, it was used during civil rights demonstrations.

And more recently, overseas, it’s become a familiar sight in protests in Hong Kong, Gaza and France.

In 1993, the United Nations banned the chemical from international warfare but that agreement included an exception. It could be used for “domestic riot control purposes.”

Today, some critics say Covid-19 complicates that.

“I agree,” says Dr. John Balmes when asked about doctors and other experts who say the use of tear gas right now is a “recipe for disaster.”

Dr Balmes is a Professor of Medicine at the University of California San Francisco and a Professor of Environmental Health at the University of California Berkeley.

Tear gas (CBS 11)

“If officials asked me for advice about crowd control during the Covid-19 pandemic, I would say ‘please don’t use tear gas’,” says Dr. Balmes who is concerned about the coughing and crying it causes in crowds.

ACLU of Texas is also telling officials, “Don’t use tear gas in crowds.”

The organization sent a letter to ten North Texas police chiefs asking them to make that a last resort.

The I-Team reached out to those ten police departments for reaction.

“Tear gas is something I think we should not completely take off the table,” says Plano Police Chief Ed Drain.

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Chief Drain is among the top commanders who got the letter. He is also among those who say they would never use tear gas during a peaceful protest; however, they do not want it taken away.

“If you take tear gas off the table, but you have to do something, you’re talking about officers having to go in hands-on or use some type of rubber bullets which can cause serious injuries,” says Chief Drain.

“I’m reserving it for a worst case scenario,” says Denton Police Chief Frank Dixon. “I’ll always say until there is a better implement to put out there, if that keeps an officer, a civilian or protester from getting hurt, because we introduced an irritant as opposed to some other means of force, I’m going to have a hard time not doing it.”

“Everything we do, you have to balance against what happens if we don’t use it,” says Irving Police Chief Jeff Spivey. He says his officers must balance the needs of protesters to have their messages heard to the needs and safety of the public.

And now, they add Covid-19 to that equation.

“We’re only going to use tear gas as a last resort when someone’s life or property is in jeopardy and there is no other way to disperse that crowd,” says Chief Spivey.

Due to possible litigation, Dallas Police Chief Renee Hall would not comment, but told the I-Team she is complying with a recent federal “judge’s preliminary injunction prohibiting” tear gas use in Dallas.

Fort Worth Police sent CBS 11 the following statement:

“As for the ACLU letter, We believe our response to the continued protests in Fort Worth have fit the model that the ACLU is calling for. We’ve allowed protests to continue while providing them a safe space to do so, and when situations have become tense we have focused on de-escalation to resolve the issue. For other tactical techniques and strategies such as tear gas, our tactical response will always be dictated by the current situation and will be the minimum response necessary to ensure the safety and wellbeing of everyone involved.”

Carrollton Police responded in an email saying, “We welcome any productive discussion… We’re always looking at current case law and research as we continually work to keep our policies up to date.”

University Park Police Chief Greg Spradlin also got the ACLU’s letter, but he says his city has never had tear gas.

“We’ve never possessed it… and we’ve had no occurrence to use it.”

Police chiefs in Lewisville, McKinney and Highland Park would not comment.

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It’s still very clear the nearly century-old gas is a topic of discussion among these top commanders, particularly during a pandemic that could be worsened by watery eyes and a cough.