Short Wave – "Black rain" in Iran and the Environmental Cost of War

Air Date: March 17, 2026
Host: Emily Kwong (NPR)
Guest: Peter Ross, Toxicologist and Senior Scientist, Raincoast Conservation Foundation

Episode Overview

This episode examines the severe environmental and health impacts resulting from recent military strikes on Iranian oil infrastructure, which led to a phenomenon called "black rain." Host Emily Kwong is joined by toxicologist Peter Ross to dissect the science of this hazardous event, the immediate and long-term dangers to public health, and the broader ecological consequences—both in Iran and potentially beyond. The discussion also raises critical questions about how the environmental cost of war is perceived and addressed in society.

Key Discussion Points & Insights

The Genesis of "Black Rain"

• Strikes on Oil Facilities: Recent U.S. and Israeli military strikes targeted Iranian oil refineries, unleashing plumes of dense, black smoke across Tehran. Reports described symptoms such as eye and throat irritation and difficulty breathing among residents.
  (00:16–01:23)
• Definition and Causes: "Black rain" occurs when large numbers of chemical pollutants, released by explosions and fires, mix with precipitation and fall back to Earth as toxic raindrops.
  • "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." – Peter Ross (01:05)
• Immediate Government Response: The Iranian government, supported by the World Health Organization, advised residents to stay indoors due to the acute health risks of breathing in these pollutants.
  (01:23–01:37)

The Chemical Cocktail: What’s in the Air?

• Explosive Reactions:
  • "What we're talking about is explosion... volatile gases... liquid fuels combusting. So we'll get fire. As a result... we're going to see a lot of different pollutants injected into the atmosphere and distributed throughout neighborhoods." – Peter Ross (03:06)
• Acute Health Concerns:
  • Immediate threats include airway irritation, exacerbation of asthma and lung conditions, increased emergency room visits, and elevated mortality rates.
    (03:36–04:47)
  • Presence of dangerous compounds such as sulfur and nitrogen oxides, carbon monoxide, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, and other volatile toxic gases.
  • "These can cause dizziness, they can cause people to faint, they can cause outright mortality." – Peter Ross (04:22)
• Long-term Dangers: As fires die down, lingering toxins pose extended threats to public health, especially through water and soil contamination.
  (04:47–05:21)

The Science of Black Rain

• Not a Cleansing Rain: Contrary to intuition, the rain doesn't "wash away" the pollutants—it spreads them. Water vapor in the atmosphere scavenges airborne toxins and deposits them across land and water systems, including crops and waterways.
  • "This will actually disperse the pollutants across croplands, into streams, rivers, creeks, lakes… down into groundwater... creating a long risk for public health." – Peter Ross (05:21)
• Water Contamination:
  • Groundwater—often relied on for drinking—can be persistently polluted by these chemicals, risking human and ecological health for years to come.
  • "If we contaminate groundwater with chemicals... then we're in it for the long haul." – Peter Ross (06:11)

Tehran’s Geography: Making Matters Worse

• Basin Effect: The city’s semi-enclosed topography, nestled at the base of the Alborz mountains, traps the polluted air, compounding exposure for its 10 million residents.
  • "We've got smoke that is lingering at different altitudes... toxic gases permeating all the streets and alleyways... not a pleasant urban environment." – Peter Ross (07:10)
• PM2.5 Dangers: Extremely fine particulate matter, invisible to the eye, can penetrate deep into lungs and even enter the bloodstream, increasing the risk for cardiac arrest, cancer, and other ailments.
  (07:10–08:07)

Comparison: Wildfire Smoke vs. War Pollution

• U.S. listeners might compare Tehran’s "black rain" to wildfire smoke, but the scale and toxicity of war-related pollution is often far worse.
  • "Local citizens have reported apocalyptic sort of smoke and visuals." – Peter Ross (08:19)
  • Masks and staying indoors offer some protection, but given the architecture and circulation in many homes, even indoor air can become contaminated.

The Realities of War Zones

• While air and water quality are grave concerns, residents’ immediate priority is physical safety from continued strikes, often making it difficult or impossible to fully shield themselves from pollution.
  • "Part of staying alive is being able to breathe and drink water. Without water, we are deceased within three to four days." – Peter Ross (09:29)
  • Acute risks affect not just people, but pets, livestock, and wildlife.
    (09:28–09:56)

Environmental Recovery: A Daunting Road

• Lessons from Exxon Valdez:
  • Full environmental recovery from oil disasters takes decades—or may never be complete. Even after 35 years, traces remain from the Exxon Valdez spill.
  • "In the case of petroleum accidents... we've really learned that it takes a long, long time to recover..." – Peter Ross (10:06)
• Magnitude in Tehran:
  • Unlike one isolated accident, strikes on multiple oil depots, refineries, and tankers represent a far bigger, more complex environmental catastrophe.
  • "Now we have several tankers on fire. We've got oil depots on fire, we've got refineries on fire... multiple sources of this complex mixture." – Peter Ross (11:04)

The Broader Conversation: The Environmental Cost of War

• Attacks on oil infrastructure during conflicts are not limited to Iran; such actions are occurring across the Middle East.
• Environmental devastation lags civil and military discourse—but may prove a longer-lasting legacy, affecting health, agriculture, and entire ecosystems.
  • "As a toxicologist, I can only say that... it’s really a crime against the environment and many innocent bystanders are going to be impacted or threatened by poor water quality, poor air quality, and basically toxic crops to consume at the market." – Peter Ross (12:03)
• Media and social media are elevating public awareness of these hidden costs, spurring new conversations about the true price of war on people and the planet.

Notable Quotes & Memorable Moments

• "We're seeing a soup of chemicals... sulfur oxides, the nitrogen oxides that form acid rain. We’re seeing metals... other carcinogens and volatile chemicals that can cause dizziness, death and or contribute to cancer."
  — Peter Ross (01:05)
• "As the fires subside, we're going to start to see longer and longer term risks to public health, water quality and the habitat for wildlife."
  — Peter Ross (04:38)
• "This will actually disperse the pollutants across croplands, into streams, rivers, creeks, lakes… down into groundwater... So in the long term, what we're talking about is really a distillation phenomena."
  — Peter Ross (05:21)
• "Part of staying alive is being able to breathe and drink water. Without water, we are deceased within three to four days."
  — Peter Ross (09:29)
• "It's really a crime against the environment and many innocent bystanders are going to be impacted or threatened by poor water quality, poor air quality, and basically toxic crops to consume at the market."
  — Peter Ross (12:03)

Timestamps for Important Segments

• 00:16–01:23: Introduction to black rain and firsthand accounts
• 03:06–04:47: Explanation of combustion pollutants and health effects
• 05:21–06:11: Discussion of black rain’s spread and groundwater contamination
• 07:10–08:07: The compounding effect of Tehran’s geography on pollution
• 10:06–11:04: Parallels to Exxon Valdez and recovery challenges
• 12:03–12:43: Reflections on environmental costs and societal awareness

Tone & Takeaways

• Scientific yet urgent: The episode balances clear explanations with an undercurrent of urgency over the environmental and human health toll of war.
• Global resonance: While focused on Iran, the discussion serves as a cautionary tale with worldwide implications—a call to consider the often-unseen, long-lasting consequences of military conflict.