Black rain fell over Tehran after strikes on oil depots during the US-Israel conflict with Iran, turning ordinary rain into a visible sign of something worse. Plumes of petrochemical smoke filled the sky and left dark residue on streets, cars and rooftops. That residue is more than an ugly stain. It can carry toxic compounds into the air people breathe, the soil where food grows and the water people drink.

What came down with the rain

The strikes released thick smoke made of petroleum byproducts. When smoke and soot mix with rain, the result is often a dark, oily precipitation. Those particles can travel, settle and then move again — into lungs, into groundwater and into the food chain.

Immediate and long-term risks

  • Respiratory exposure: Tiny particles can be inhaled, irritating and damaging airways and lungs.
  • Soil contamination: Toxic compounds can settle on soil, affecting agriculture and plants.
  • Water pollution: Runoff can carry chemicals into rivers, wells and reservoirs.
  • Chronic health concerns: Some petrochemical pollutants are linked to higher cancer risk and other long-term illnesses.

Those effects do not stop when the smoke clears. Chemical residues can persist, creating ongoing health and environmental challenges for communities already living under conflict conditions.

Why this matters

When the air becomes part of the battlefield, civilians face a new kind of harm that is less visible than a blast but just as damaging over time. Contamination that moves through air, soil and water multiplies the impact beyond the immediate blast zones and into everyday life.

Voices on the issue

The conversation included Narges Bajoghli, a cultural anthropologist at Johns Hopkins University, who helped unpack the human and social dimensions of environmental contamination in conflict settings.

Episode production credits

  • Produced by: Noor Wazwaz, Marcos Bartolomé and Sarí el-Khalili
  • Additional production: Catherine Nouhan and Tuleen Barakat
  • Guest host: Tamara Khandaker
  • Edited by: Sarí el-Khalili
  • Sound designer: Alex Roldan
  • Video editors: Hisham Abu Salah and Mohannad al-Melhem
  • Executive producer: Alexandra Locke

Published on: 25 March 2026