War is measured first in lives lost, families uprooted and neighbourhoods reduced to rubble. But there are also deadly consequences that are often ignored. Pollution caused by war can settle over cities, contaminate water and soil, and shape public health long after the fighting is over. This is the case with the Iran war.

The six weeks of bombardment in Iran and the Gulf that saw attacks on energy infrastructure have already taken a toll. Burning fuel tanks send toxic particles into the air, while debris, run-off and oil residues threaten coastal waters and marine ecosystems across the Gulf, where pollution can spread far beyond the immediate strike zone.

The region has seen before how long such damage can last. During the 1991 Gulf War, retreating Iraqi forces set fire to more than 600 Kuwaiti oil wells. For months, dense smoke covered the skies, causing widespread air pollution, contamination of soil and groundwater across the Gulf – and a generation of health consequences.

The United Nations later treated much of that destruction as compensable harm: Through the UN Compensation Commission, Iraq ultimately paid more than $50bn for damage linked to oil fires, marine pollution and ecosystem loss.

Ukraine offers another terrifying example. The ongoing war has created a toxic legacy, with attacks on fuel depots, industrial sites, chemical warehouses and energy infrastructure contaminating air, rivers and farmland across large parts of the country. UN agencies and Ukrainian organisations have documented thousands of incidents of environmental harm since the invasion began, including fires at oil facilities, deforestation, contamination from damaged industrial sites, and widespread risks to water systems.

Fossil fuel systems are especially vulnerable in war because they concentrate combustible fuels and hazardous chemicals. When oil depots, refineries or pipelines are struck, they ignite fires that release toxic gases, carcinogenic particles and residues, contaminating surrounding land and water for years.

Conflict also erodes oversight. When governance collapses, environmental regulation and corporate accountability often collapse with it, leaving communities living in the shadow of fossil fuel infrastructure to absorb pollution and health harms long after headlines fade.

Routine maintenance on oil pipelines, for example, has become difficult in volatile security environments in Yemen and Sudan, resulting in contaminated water and farmland. In Yemen, years of conflict left the FSO Safer tanker without maintenance, threatening to cause one of the world’s worst potential oil spills before an emergency transfer operation finally took place in 2023.

The climate dimensions compound the harm. Militaries themselves were responsible for an estimated 5.5 percent of global greenhouse gas emissions in 2022, largely from the burning of high-emitting fossil fuels. Yet military emissions are not comprehensively included in international climate accounting – an exemption long pushed for by the United States. As military spending surges globally, so too does its largely uncounted carbon footprint.

Conflict also drives environmental harm beyond energy systems. When electricity collapses and fuels become scarce, households often turn to charcoal and firewood, accelerating forest loss in fragile areas. Researchers tracking conflict zones have found that deforestation frequently rises where governance weakens and fuel alternatives disappear.

Sudan has seen this dynamic around Khartoum and other urban areas, with significant loss of tree cover since the war began in 2023 –  tree cover that serves important ecosystem functions, including retention of groundwater.

War also creates hazards beyond fossil fuels themselves. Bombardment pulverises buildings, roads and industrial sites, releasing dust laced with silica, heavy metals, and other toxins into the air. These particles can scar lungs and aggravate chronic respiratory illness. Rebuilding destroyed cities adds another climate burden: Cement and steel production are among the most carbon-intensive industrial processes in the world, meaning reconstruction often generates another surge of emissions embedded in new concrete and infrastructure.

Renewable energy systems can also be damaged in conflict, but their environmental footprint is fundamentally different. A destroyed solar installation does not spill crude into rivers, and a damaged wind turbine does not ignite refinery-scale fires or release toxic benzene into nearby neighbourhoods.

That matters when countries rebuild. Energy systems reconstructed around oil storage, gas transport and centralised fuel infrastructure remain vulnerable both to pollution and to global price shocks whenever conflict threatens major supply routes such as the Strait of Hormuz. More distributed renewable grids cannot remove the risks of war, but they can reduce both the toxic aftermath and the global economic shock that follows.

Wars will continue to destroy infrastructure. Whether they also leave behind decades of pollution depends in part on what kind of energy systems are rebuilt when the fighting stops.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.