You're listening to Shortwave from NPR.

Lisa Song is an environment reporter with ProPublica

and her recent reporting tackles something we've all seen floating in the air these weeks of protests.

On TV, maybe even in person.

Tear gas.

I started seeing all the reports of law enforcement using tear gas all over the country.

You know, in protest after protest, I saw the photos of the white smoke coming up.

Videos of protesters desperately washing out their eyes.

People are choking and gasping for air.

Tear gas clearly makes it hard to breathe.

I've still got a very sore, what feels like a burnt throat from whatever it was.

And I just thought, what exactly is tear gas?

It doesn't seem like a good idea to use in the middle of a respiratory pandemic.

We are moving back down the streets as protesters are now thinking of some of those canisters

and trying to throw them back at police.

And this seems unprecedented.

Do we actually have any science about whether it's safe or not?

So Lisa set out to answer those questions.

That's when I started talking to researchers and scientists

and really getting a sense that the combination of the way that tear gas is being used in these protests,

the huge quantities, the frequency with which it's used,

the way police are using it is really a cause for concern.

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