You're listening to Shortwave from NPR.

The U.S. and Israel launched military strikes on Iran late last month.

And those strikes have continued. Among the targets this month were oil refineries and depots in and around the capital city of Tehran.

And that released thick plumes of black soot and smoke that drifted across the city.

Some Iranians said it burned their eyes and throat and that it was painful to breathe.

And then came the Black Rain, which Tehran residents said left behind a dark, oily residue.

That's what they told the BBC.

Black rain is a phenomenon caused by large amounts of chemical pollutants in the air. That's according to Peter Ross,

a toxicologist and senior scientist at Rain Coast Conservation Foundation in Sydney, British

Columbia, in Canada. We're seeing a soup of chemicals, including the sulfur oxides, the nitrogen oxides that form acid rain.

We're seeing metals. We're seeing other carcinogens and volatile chemicals that can cause dizziness, death, and or contribute to cancer.

And after the rain fell, Iran's government urged residents to stay indoors.

The World Health Organization backed them up.

They warned Iranians of the potential health risks associated with breathing in these high levels of toxic pollutants.

The black rain and the acidic rain coming with it is indeed a danger for the population.

Ali Jafarian, Iran's deputy health minister, told Al Jazeera that this rain is already

contaminating the soil and water supply, which could indicate longer-term consequences for public health as well as the local

environment.

So today on the show, Iran's Black Rain.

What we know about the chemicals contained in it, the potential effect of those pollutants,

both short and long term, and what it all says about the environmental cost of war.

I'm Emily Kwong, and you're listening to Shortwave, a science podcast from NPR.

...