Tehran's Black Rain: The Environmental War Nobody Declared

Oil facility strikes have created an unprecedented pollution crisis across a city of nearly 10 million. Scientists are calling it something they've never seen before in modern warfare. The WHO is alarmed. Nobody planned for this - and nobody knows how long the damage will last.

Smoke columns from struck oil facilities are visible across Tehran for the second consecutive week. Photo: Unsplash

On Sunday morning, it rained in Tehran. But the rain was black.

Residents in one of the world's most densely populated capitals watched dark droplets streak their windows and pool on their balconies - contaminated rainfall carrying the particulate residue of burning oil refineries, fuel depots, and storage tanks struck by US-Israeli airstrikes over the previous 10 days of Operation Epic Fury.

A woman in her 20s, speaking to BBC Persian on Saturday, captured it plainly: "I can't see the Sun. There is a horrible smoke. It's still there. I'm very tired."

That exhaustion runs deeper than a lost night of sleep. Scientists examining satellite imagery and atmospheric data say Tehran is experiencing a form of air pollution that has no real precedent in the history of modern urban warfare. The city's 9.7 million residents - already living under near-nightly air raids, power outages, and communications disruptions - are now breathing a chemical cocktail that experts say will cause damage measured not in days, but in decades.

The World Health Organization has issued a formal warning. Scientists at three British universities have characterized the pollution as "unprecedented." The Conflict and Environment Observatory - which monitors environmental damage in war zones - says nothing like this has been observed before in an urban combat environment of this scale.

The military campaign against Iran's nuclear program and missile infrastructure has dominated 12 days of headlines. The environmental catastrophe unfolding across Tehran has received far less attention. This is an attempt to correct that.

What Is Being Hit - The Oil Infrastructure Under Attack

Oil refineries contain hundreds of volatile compounds that combust and disperse when struck. Photo: Unsplash

BBC Verify's analysis of satellite imagery has confirmed strikes on at least four oil facilities in and around Tehran since the US-Israeli campaign began on February 28. The Israel Defense Forces officially acknowledged striking "fuel depots" near the capital in a post on X on March 7.

The two primary sites still burning as of March 9 - confirmed by satellite imagery captured that day - are the Shahran fuel depot in Tehran's northwest and the Tehran oil refinery in the city's southeast. Between them, these are two of Iran's most significant petroleum processing and storage nodes. They are also positioned inside a city basin already prone to severe air quality problems due to geography and traffic density.

The Tehran refinery is not an isolated industrial site. It sits in close proximity to residential neighborhoods. The Shahran depot - visible in satellite images surrounded by burning oil tankers, blackened infrastructure, and active fires even on Sunday morning after emergency workers had spent days attempting to control the blazes - is in the city's northwest, near populated suburbs.

Emergency footage verified by BBC Persian showed "huge fireballs illuminating the night sky" over the refinery following reported strikes in the early hours of Saturday, March 8. Social media video from the same night showed flames leaping above Tehran's skyline with smoke plumes spreading across the city in multiple directions, depending on wind patterns.

The IDF and Pentagon have declined to comment specifically on strikes targeting the oil infrastructure. The IDF's stated focus has been Iran's ballistic missile capabilities, naval assets, and proxy network command structures - but the oil facilities have been hit as part of what US officials describe as a campaign to degrade Iran's economic capacity to sustain military operations.

The Pentagon, as of this writing, has not disputed the BBC Verify findings of four confirmed strikes on Tehran-area oil facilities. It has declined to comment.

The Science of Black Rain - What is Actually Falling on Tehran

Black rain is not metaphor. It is a documented meteorological phenomenon - rainfall that has absorbed soot, hydrocarbons, and other combustion products from a sustained and intense fire source, turning the precipitation visibly dark and coating surfaces with residue.

The most historically significant instances of black rain occurred in Hiroshima and Nagasaki in August 1945, following the atomic bombings - where the fires produced carbon and ash that mixed with rain falling hours after the blasts. Those events left lasting environmental and health consequences that researchers documented for decades afterward.

Tehran's black rain is different in mechanism but similar in its public health implications. The fuel depots and oil refineries burning across the city are not producing a single type of pollutant. They are releasing a complex mixture that scientists describe as genuinely alarming in its breadth.

Dr. Akshay Deoras, a research scientist at the University of Reading, explained the mechanism to BBC Verify:

"The raindrops acted like little sponges or magnets, collecting whatever was in the air as they fell, which is why residents observed what's being described as 'black rain.'" - Dr. Akshay Deoras, University of Reading, via BBC Verify

But the real issue is not the rain itself. It is what the rain is collecting.

When oil is burned - particularly when there is incomplete combustion due to sudden ignition from a missile strike rather than controlled industrial burning - the process releases a suite of toxic compounds: carbon monoxide instead of carbon dioxide, particulate matter, sulphur and nitrogen oxides, heavy metal compounds, polycyclic aromatic hydrocarbons, and aerosolized oil droplets.

Sulphur and nitrogen oxides are particularly problematic because they dissolve in atmospheric moisture to form acids - creating acid rain effects on top of the existing particulate hazard. Oil droplets suspended in air coat the respiratory tract differently from typical urban particulate matter like vehicle exhaust or dust. They carry dissolved chemical compounds directly into lung tissue in a way that is harder for the body to process or expel.

Professor Eloise Marais, professor of atmospheric chemistry and air quality at University College London, put the scale of the situation plainly:

"In most circumstances, this kind of pollution would only be seen from a very, very severe industrial accident where an entire refinery explodes." - Prof. Eloise Marais, University College London, via BBC Verify

Tehran is not experiencing the equivalent of one refinery accident. It is experiencing the equivalent of multiple simultaneous refinery explosions in a city that already has some of the worst baseline air quality in the Middle East, surrounded by mountains that trap pollutants in the basin during low-wind conditions.

Unprecedented - What Scientists Have Not Seen Before

The word "unprecedented" gets overused in crisis reporting. Researchers are using it here with deliberate precision.

Doug Weir, director of the Conflict and Environment Observatory - an organization that specifically tracks environmental damage from military operations worldwide - stated the case directly:

"What's unusual about Tehran is we haven't observed these attacks in such a densely populated area before. Often these oil field sites are quite far out in the countryside. People in Tehran are exposed to a huge range of substances in this black rain - not just oil." - Doug Weir, Conflict and Environment Observatory, via BBC Verify

Dr. Deoras echoed this assessment, noting the particular characteristic of the Tehran situation: "What has happened in Iran is definitely unprecedented because it's all coming in from missiles dropping in and airstrikes on oil refineries." He characterized the mix of pollutants as "definitely unusual" compared to city smog in Beijing or Delhi - different not just in scale but in chemical composition.

The Conflict and Environment Observatory has documented oil infrastructure strikes in previous conflicts - the Persian Gulf War in 1991 saw Iraqi forces set fire to hundreds of Kuwaiti oil wells, creating the "oil lake" and atmospheric pollution events that affected regional health for years. Strikes on oil infrastructure in the Syrian civil war caused localized contamination. US and coalition strikes on ISIS-controlled oil facilities in Syria and Iraq created pollution incidents.

But those events occurred primarily in rural or semi-rural areas, or in cities without Tehran's population density of approximately 11,900 people per square kilometer. The scale of simultaneous exposure of a mega-city population to this type of chemical mixture from struck oil infrastructure is, according to Weir, something the Conflict and Environment Observatory has no direct precedent for in its database.

A precise assessment of actual air quality levels in Tehran is not possible from outside the country. Iran's government has not released ground-based air monitoring data since the strikes began. Satellite data is difficult to interpret precisely due to wind variability, cloud interference, and the difficulty of distinguishing industrial smoke from atmospheric particulate at scale.

What scientists can confirm is directional: the pollution is severe, the chemical composition is unusual and multi-hazard, and it is affecting a city of nearly 10 million people during a period when evacuation is not an option for the vast majority of residents.

Ten Million People Who Cannot Leave

Tehran sits in a mountain basin that traps air pollution - a geography that worsens the impact of sustained oil fires. Photo: Unsplash

Tehran is not a city that can be evacuated. It is Iran's capital, its financial center, its industrial hub, and home to roughly 10% of the country's total population. The broader metropolitan region - including cities like Karaj and Rey - adds another 5-6 million people to the exposure zone.

Under ordinary circumstances, a pollution event of this scale would trigger public health alerts, mass distribution of protective equipment, and official guidance on shelter-in-place procedures. None of that is available to Tehran residents right now.

Iran's government communications infrastructure has been severely degraded. The country has experienced periodic internet shutdowns and telecommunications disruptions during the war. State media continues to broadcast but has focused on military framing of events rather than public health guidance. There is no evidence of organized mask distribution, air quality advisories, or government-coordinated civilian health response to the pollution crisis.

Residents who have spoken to international media describe a city gripped by exhaustion and helplessness. A Tehran woman contacted by BBC Persian said she could "smell the burning" and couldn't see the sun. Iranians in Tehran and Karaj told the BBC they are "exhausted and struggling to sleep after 10 days of Israeli and US attacks."

The pollution exposure is not uniform across the city. Those living closest to the Shahran depot in the northwest and the refinery in the southeast face the highest concentrations. But Tehran's mountain basin geography - the Alborz range to the north creates a natural bowl that traps air during temperature inversions - means that even residents in ostensibly safer districts are not meaningfully protected.

Tehran already has some of the worst air quality in the Middle East under normal conditions. A 2019 report by IQAir ranked Tehran among the 10 most polluted large cities in the region. The baseline the current crisis is building on was already medically significant. Adding multiple simultaneous oil facility fires on top of that baseline creates a public health emergency that specialists say has no comparable modern urban precedent.

Children, elderly residents, and people with pre-existing respiratory or cardiovascular conditions face the highest immediate risk. But experts emphasize the exposure is not limited to vulnerable populations - sustained high-concentration exposure to the compounds being released from the burning oil facilities carries serious risk for healthy adults as well.

The WHO Warning - What the International Health System Is Saying

The World Health Organization's director-general, Dr. Tedros Adhanom Ghebreyesus, has issued a formal statement expressing "great concerns" for the health impacts of the conflict on Iran's civilian population.

The WHO's concern extends beyond the pollution crisis, but the statement specifically called out strikes on oil facilities as a particular hazard:

"Damage to oil facilities risks contaminating food, water and air - hazards that can have severe health impacts especially on children, older people, and people with pre-existing medical conditions." - Dr. Tedros Adhanom Ghebreyesus, WHO Director-General

The WHO has not been granted access to Iran to conduct independent health assessments since the war began. Iran's health ministry has released limited information about civilian casualties from direct strikes, but has not publicly released systematic data on pollution-related health presentations at hospitals and clinics.

Professor Anna Hansell, professor of environmental epidemiology at the University of Leicester, described both the immediate and long-term health stakes:

"These very intense exposures of particulates have immediate impacts on the lungs. But they can also have quite long-lasting effects over many years afterwards, on both respiratory systems and increasing cancer risk." - Prof. Anna Hansell, University of Leicester, via BBC Verify

The specific compounds being released from oil facility fires - polycyclic aromatic hydrocarbons, benzene derivatives, heavy metals - are established carcinogens. Exposure to them during sustained high-concentration events is linked to elevated long-term rates of lung cancer, bladder cancer, and leukemia. These effects do not manifest in weeks or months. They appear years and decades later, in epidemiological data that will be difficult to attribute cleanly to any single cause.

This is what makes the environmental dimension of the Iran war different from its more immediately visible military dimensions. The missile exchanges, the naval engagements, the air defense duels - these produce casualties that are counted in real time. The pollution crisis is producing harm that will be counted years from now in cancer registries and respiratory disease statistics, if Iran's health system survives intact enough to maintain them.

The rain that fell on Sunday - absorbing those hydrocarbons, those metal compounds, that sulphuric acid - did not disappear when it hit the ground. It contaminated soil. It entered Tehran's drainage systems. It will, as BBC Weather forecasts suggest continued rainfall through Thursday, wash pollutants into waterways and agricultural runoff. The contamination will follow Tehran's water cycle for months after the fires stop burning, if they stop burning.

Is Striking Oil Infrastructure a War Crime?

International humanitarian law governing attacks on civilian infrastructure is complex, and the debate over oil facility strikes has a long history in conflict law. The central question is whether an oil facility constitutes a legitimate military target, and under what circumstances attacking it violates the proportionality and distinction principles of the laws of armed conflict.

The US and Israel have both indicated that Iran's oil infrastructure is being targeted as part of a campaign to degrade Tehran's financial and military capacity to sustain the war. Under the laws of armed conflict, a dual-use facility - one with both civilian and military functions - can be a legitimate target if the military advantage anticipated from its destruction is not "excessive in relation to the concrete and direct military advantage anticipated."

The proportionality calculus for striking oil refineries in a city of 10 million, producing environmental contamination that scientists describe as unprecedented in its civilian health impact, is the question that international law scholars are now beginning to raise.

Human Rights Watch has previously taken the position, in the context of Israeli strikes on Hezbollah-linked financial institutions in Lebanon in 2024, that "an armed group's use of a financial institution... does not amount to an effective contribution to military action, and therefore it is not a lawful military target under the laws of war." The principle - that civilian utility of a facility must be weighed against military necessity - applies directly to oil infrastructure that serves civilian transportation, heating, and power generation alongside any military supply function.

Iran's oil refineries supply fuel for civilian vehicles, generators, heating systems, and agricultural equipment. The Tehran refinery alone serves a civilian population that has no alternative fuel supply. Its destruction deprives civilians of resources they depend on for survival, particularly during Ramadan when nighttime activity and cooking demand is high, and during spring weather transitions that require heating in Tehran's high-altitude climate.

No court has yet been asked to rule on the legality of the specific strikes in this conflict. The International Criminal Court does not have jurisdiction over US forces, and Israel's status under ICC jurisdiction is disputed. But the legal debate is running in academic and policy circles, and the environmental evidence is accumulating in a form that will be available to future tribunals or historical inquiries.

The United States and Israel have not addressed the environmental dimension of the strikes in their public communications. The Pentagon's press secretary has described Operation Epic Fury as targeting Iran's military capabilities, not its civilian infrastructure. The IDF's characterization of fuel depot strikes as legitimate military targeting has not been publicly contested by its own leadership.

Timeline: The Escalation That Led to Black Rain

What Comes After - Long-Term Contamination

Assuming the oil facility fires are eventually extinguished - either through emergency response efforts or because the facilities are damaged beyond the point where they can continue to burn - the contamination problem does not end.

Oil fires leave behind physical residue: oil-soaked soil, chemical contamination of groundwater, metallic deposits on surfaces. In a city, this residue settles on rooftops, streets, parks, school playgrounds, and food markets. It enters the urban water drainage system. It coats vegetation. During dry periods, wind can resuspend fine particles from contaminated surfaces back into the air - creating secondary exposure events weeks or months after the primary fires are out.

BBC Weather data suggests Tehran faces continued rainfall through Thursday and beyond. That rainfall will accelerate the transport of surface contamination into drainage systems and watercourses. Iran's water management infrastructure - Tehran's water supply relies on rivers, reservoirs, and aquifers in the Alborz region north of the city - will be stressed by pollution entering the watershed.

Iran's agricultural land in the greater Tehran region grows food consumed across northern Iran. Acid rain effects from sulphur and nitrogen oxide emissions will affect soil pH and crop yield in affected areas. These agricultural impacts will not appear immediately, but they will compound through growing seasons.

Doug Weir of the Conflict and Environment Observatory noted the persistence of risk even after rain clears the immediate atmosphere:

"That does not mean the risks of the pollutants disappear. They can enter rivers and other waterways, or if they settle and the ground dries then winds can pick them up and they can become resuspended in the air." - Doug Weir, Conflict and Environment Observatory

The cleanup requirements, once the war ends, will be substantial. The 1991 Gulf War oil fires in Kuwait required years of remediation. The Kuwaiti fires were in desert terrain with far lower population density than Tehran. The tools used for oil well fire suppression and environmental remediation in rural Kuwait are not directly translatable to a dense urban environment.

Iran's economic capacity to fund environmental cleanup after the war will be severely constrained by the war's destruction. The oil infrastructure being struck is simultaneously Iran's primary source of export revenue and the source of the pollution now contaminating its largest city. The country will emerge from this conflict needing to rebuild its energy sector while simultaneously remediating the environmental damage from that sector's destruction.

The War Expands - Beirut and the Broader Escalation

While Tehran's environmental crisis unfolds, the geographic scope of the conflict continued to expand Monday. Israel struck the Ramada Plaza hotel in the Raouche neighborhood of central Beirut in the early hours of March 8 - the first strike in this war's Lebanese phase to hit the city center, targeting what the IDF said was a secret meeting of Iranian Quds Force operatives.

The strike killed five men. The IDF identified three as senior Quds Force commanders: Majid Hassani, described as responsible for transferring funds to Iranian proxies in Lebanon; and intelligence figures Alireza Bi-Azar and Ahmad Rasouli. Iran's UN mission contradicted the IDF characterization, issuing a letter calling the four Iranians killed "diplomats of the Islamic Republic of Iran" and condemning what it called a "heinous crime" and "grave terrorist act."

The hotel strike illustrates a strategic pattern that the Tehran pollution crisis makes concrete from a different angle: the war's targeting logic is expanding beyond military hardware. Oil infrastructure, financial institutions (Israel has also struck branches of Hezbollah-linked Al-Qard Al-Hassan in Lebanon), and now hotels being used as temporary headquarters by intelligence operatives - the definition of legitimate target is being stretched in ways that directly affect civilian populations and civilian infrastructure.

Meanwhile, Defense Secretary Pete Hegseth, speaking Monday, vowed that today - Day 12 of Operation Epic Fury - would be "the most intense day" of US strikes against Iran yet. Iran launched new ballistic missiles toward Israel even as Hegseth spoke, with the IDF activating intercept procedures and mobile phone alerts across threatened areas.

Iran's missile capability has been degraded - US officials cite a greater than 86% reduction in ballistic missile attacks since the campaign began - but it has not been eliminated. The war is entering a phase where both sides show no indication of stopping, where the environmental and humanitarian costs are compounding daily, and where the exit conditions remain genuinely unclear.

White House Press Secretary Karoline Leavitt said the war will not end until Iran's "complete and unconditional surrender, whether they say it or not." Hegseth said the endgame is whatever is "in America's interests." Iran's new acting leadership, under pressure from US-Israeli strikes that have dismantled the previous command structure, has continued to resist.

In Tehran, the fires burn. The air is dark. The rain falls black. And nobody who matters is talking about it.

The Slow Casualty

Wars produce two types of casualties: the ones that are counted immediately, and the ones that take years to appear in death certificates.

The Iranian government has provided casualty figures for direct strike deaths. The US and Israeli militaries have provided figures for missile intercepts and naval engagements. Journalists in the region have documented civilian deaths in Gaza, Lebanon, and Iran with extraordinary risk to their own lives - 270 journalists killed in this conflict zone since 2024, according to reporting by this bureau.

Nobody is counting the slow casualties. The Tehran residents who will develop lung cancer in 2031. The children who are breathing black rain this week and who will face reduced lung capacity for the rest of their lives. The elderly residents with pre-existing heart conditions whose risk of cardiac events increases significantly with sustained exposure to fine particulate matter at the concentrations now present in Tehran's air.

Professor Hansell's warning - that "long-lasting effects over many years afterwards, on both respiratory systems and increasing cancer risk" should be expected - is not speculation. It is based on established epidemiology from industrial accident studies, from long-term analysis of pollution exposure cohorts, and from the documented health aftermath of previous conflicts involving oil infrastructure destruction.

The slow casualty count from Tehran's black rain will not be reported in real time. It will not appear in Operation Epic Fury's official tally. It will surface years from now in comparative mortality data, in hospital admission rates, in the quiet statistics of a city carrying invisible wounds that the war's architects never planned to account for.

Wars end on paper. The damage they leave in soil, water, and lung tissue does not.