March 9, 2026

expert reaction to the impacts of air strikes on oil refineries in the middle east

Scientists comment on the impacts of air strikes on oil refineries in the Middle East. 

Prof Andrea Sella, Professor of Inorganic Chemistry, University College London (UCL), said:

“To call it a “poison gas” attack is highly misleading in my view, and it is important to make sure that the language we use is measured. That said, the explosions will have exposed the local population to all manner of undesirable and toxic chemical species, a problem that is well known to accompany warfare.

“This was the deliberate destruction and ignition of storage tanks containing crude oil. Much of this material is quite viscous and burns poorly – this is a key reason why we have oil refineries: to convert this stuff into much more fluid and faster burning material that will combust efficiently inside engines.

“Because crude oil burns so poorly and at relatively low temperature it is not converted neatly into carbon dioxide and water. And in any case crude oil is not all hydrocarbon (compounds of carbon with hydrogen) – there are often significant amounts of sulphur in the oil that would normally be removed as part of the processing in refineries (hydrodesulfurization) because when they are burned they produce acidic sulphur acids (the origin on acid rain used to plague the Northern hemisphere). Other elements present – including metals – will also be spread indiscriminately.

“Crude oil (and heavy hydrocarbons like diesel and other heavy fuel oils) burns with very smoky/sooty flames, the smoke will often be acidic because of the sulphur, and the low combustion temperatures lead to other chemistry. Even with refined fuels we have exhaust catalysts that are designed in part to deal with what is not fully combusted. Additionally, significant amounts of the oil will be converted into aerosol, minute droplets of oily mist that will be spread over a wide area.

“There will be a real cocktail of chemistry including significant amounts of aromatic compounds that are known to interact with DNA and have been linked to cancers. Whether or not this manifests will depend strongly on how long and serious the exposure of is any individual.

“And on top of this, once the containment provided by the tanks and pipes is destroyed the material will flow everywhere leaving a mess of harmful material that permeates the soil and coats everything else. There is the potential for contamination of drinking water supplies.

“In summary, there is no question that the smoke from such fires is very harmful and we can anticipate a lingering legacy of respiratory and other illnesses into the future.”

Prof Zongbo Shi, Professor of Atmospheric Biogeochemistry, University of Birmingham, said:

“Explosions in oil refineries or storage facilities can generate substantial air pollution through large-scale combustion of petroleum products and infrastructure. They release not only conventional pollutants, including fine particulate matter (PM₂.₅) and sulfur dioxide (SO₂), but also toxic volatile organic compounds (VOCs) and other hazardous combustion by-products. Combustion of sulfur-containing fuels can produce elevated SO₂ concentrations, potentially contributing to acid deposition. Exposure to these pollutants is known to increase the risk of acute respiratory and cardiovascular health effects, particularly among vulnerable populations such as infants, older adults, and individuals with pre-existing conditions including asthma and chronic obstructive pulmonary disease (COPD).”

Dr Akshay Deoras, Research Scientist, University of Reading, said:

“There are reported fears of acid rain over Tehran, but what we’re seeing is really the result of a combination of human and natural factors. The air strikes on oil depots released soot, smoke, oil particles, sulphur compounds, and likely heavy metals and inorganic materials from the buildings, whilst a low‑pressure weather system, which typically sweeps across Iran and West Asia around this time of year, created conditions favourable for rainfall. 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.’ It’s not that the strikes or resulting smoke created the rain; rather, rain drops picked up pollutants already present in the atmosphere.

“In terms of atmospheric chemistry, the oil fires produce sulphur and nitrogen compounds that could form acids if they dissolve in rainwater. The risks to human health come from inhaling or touching the smoke and particles. Immediate impacts can include headaches, irritation of the eyes and skin, and difficulty breathing—particularly for people with asthma, lung disease, older adults, young children, and those with disabilities. 

“Whilst the weather system that brought rain over Tehran is now moving eastward into other parts of Asia, further ‘black rain’ is unlikely there. Even in places where the system is moving, such as northern India, similar black rain is also unlikely, since such air‑quality‑driven impacts on rainfall are generally localised.“

Declared interests:

Dr Akshay Deoras: “No conflict of interest to declare. “

Prof Andrea Sella: “I have no interest”

For all other experts, no reply to our request for DOIs was received.