In the aftermath of recent U.S.-Israeli airstrikes targeting oil depots in Iran, alarming reports have emerged of what is being described as “acid rain” falling over parts of the country. Residents affected by the bombings have experienced symptoms such as headaches, breathing difficulties, and observed oily, black rain settling on buildings and vehicles. Iran’s Red Crescent Society has issued warnings, highlighting that the rainfall following the attacks could be “highly dangerous and acidic,” raising serious health and environmental concerns.
Gabriel da Silva, an associate professor of chemical engineering and atmospheric chemistry at the University of Melbourne, explains that the situation goes far beyond what the term “acid rain” typically suggests. As an expert in air pollution, da Silva emphasizes that this rain likely contains a complex mixture of harmful substances, including acids but also numerous other toxic pollutants that pose significant risks to human health and the environment both immediately and for years to come.
One key reason for the occurrence of this black, oily rain lies in how air pollutants are naturally removed from the atmosphere. Rain serves as a cleansing mechanism, washing pollutants out of the air as water droplets fall to the ground. When air contains high levels of contaminants—as would be the case after large explosions and fires at oil depots—those pollutants become embedded in the rain. Thus, the “black rain” is a visible indicator that local air quality has been severely compromised.
The black rain likely contains toxic hydrocarbons, ultrafine particulate matter known as PM2.5, and carcinogenic compounds called polycyclic aromatic hydrocarbons (PAHs). Additionally, the explosions and fires may release heavy metals and inorganic chemicals originating from the materials involved in the blast, further complicating the chemical cocktail raining down on the affected areas. These substances are hazardous both when inhaled and when they come into contact with skin or are ingested through contaminated water.
Another dangerous component of the smoke released during the airstrikes includes sulfur dioxide and nitrogen dioxide gases. These compounds react in the atmosphere to form sulfuric and nitric acids, which mix with rainwater to create what is conventionally known as acid rain. Historically, acid rain has been associated mainly with sulfur dioxide emissions from burning fossil fuels; although sulfur content in crude oil is often removed during refining, the burning of oil depots releases sulfur compounds directly into the atmosphere, contributing significantly to acid rain formation.
The health risks posed by this black smoke and contaminated rainfall are considerable. In the short term, exposure can cause headaches, respiratory distress, and exacerbate pre-existing conditions such as asthma and other lung diseases. Vulnerable groups—including young children, the elderly, pregnant women, and individuals with disabilities—face heightened risks. For pregnant women, exposure to toxic air pollutants is linked to adverse outcomes like low birth weight.
Long-term exposure to the pollutants present in the smoke and rain increases the risk of serious health problems, including various cancers, neurological disorders such as cognitive impairment, and cardiovascular diseases. Ultrafine particles like PM2.5 can penetrate deep into the lungs, enter the bloodstream, and trigger systemic effects throughout the body. Carcinogenic PAHs also contribute to these health threats.
Beyond human health, the environmental impact is equally worrying. As the polluted rainwater soaks into the ground and waterways, it poses a threat to aquatic ecosystems and may contaminate drinking water supplies. Moreover, the deposition of harmful compounds on surfaces such as buildings and roads creates a reservoir of pollutants that can be resuspended into the air by wind or human activity, prolonging exposure risks.
The current situation in Iran is not unique in the context of warfare-related environmental damage. Past conflicts, such as those in Iraq and Kuwait, have demonstrated the devastating environmental and health consequences of targeting oil infrastructure or using burn pits for waste disposal. Returning service members from these conflicts have suffered long-term health problems, and it is reasonable to infer that local populations, exposed directly and continuously, experience profound and lasting adverse effects.
In terms of immediate protective actions, experts advise that people in affected areas should limit exposure to the toxic smoke and contaminated rain. Practical steps include wearing masks or face coverings, staying indoors with windows and doors closed, and avoiding outdoor activities during heavy smoke or rainfall events. Cleaning hard surfaces indoors can help reduce contact with deposited pollutants. However, implementing these precautions amid the chaos and disruption caused by war presents significant challenges.
The broader implications of the environmental and health impacts of military actions targeting oil infrastructure call for increased awareness and consideration in conflict zones worldwide