Less than an hour after Chernobyl’s Reactor 4 tore apart during an overnight safety test, the first casualties started arriving at Pripyat Hospital—men burned and sickened as radioactive debris climbed into the atmosphere and drifted across Europe.
In the early confusion—around 2am on April 26, 1986—staff had almost no clear instructions. Injured plant workers and firefighters kept coming through the doors with wounds that resembled severe burns, and nurses reached for a familiar home remedy: milk.
In the Soviet Union, milk was widely believed to calm burns and help “wash out” poisons. But against the invisible damage already progressing through the men’s bodies, it offered no real protection.
As the flow of patients increased, the hospital team began to understand they were witnessing something far beyond an ordinary industrial accident. One particular sign stood out immediately—an alarming, deep red discoloration that spread across many faces.
Several of the men had already entered the earliest stages of acute radiation injury after time spent near Reactor 4—where, on the roof and surrounding areas, a lethal dose could be absorbed in minutes.
“I was running down the corridor and it felt like the floor was moving,” firefighter chief Petr Khmel recalled on the documentary Chernobyl: 48 Hours to Escape, explaining that he had only a cloth respirator that provided no meaningful protection.
“I tore it off, and a fountain of blood shot out of my mouth,” Khmel said.
Others were sent through decontamination showers and emerged vomiting, disoriented, and unable to hear—symptoms consistent with some of the highest radiation exposures ever documented—within roughly an hour of the blast.
By about 6am, as more men were triaged and admitted, the hospital shifted into crisis mode. Non-exposed patients were moved out, rooms were cleared, and floors were scrubbed. Still, the staff had little to prepare them for what became obvious as daylight arrived on April 26.
Paramedic Lyudmila Dzhulai, who was among the nurses on shift that night, described the unforgettable look of the “walking wounded” brought in from the plant.
“They were brought here with faces red and burned,” she told the documentary, adding: “Radiation burns are not thermal burns, there are no blisters.”
She went on to describe what many later called a “nuclear tan.” “The face is simply crimson, even burgundy,” she said. Despite the harmless sound of the phrase, this flushing can indicate catastrophic exposure and a grim prognosis.
The intense redness is linked to widespread cellular injury caused by penetrating gamma rays and beta particles striking tissue and DNA. As atoms are ionized and electrons are stripped away, unstable free radicals form and help trigger large-scale cell destruction.
That destruction spreads through the body, including the skin’s deeper layers—especially in those who took massive doses in a short period. On the face, the effects could be particularly visible.
One reason is vascular density: the face contains many blood vessels, and the body can respond to severe injury by widening them dramatically (vasodilation) in an attempt to deliver immune and repair signals. The result is pronounced redness and swelling.
As damaged tissue breaks down, chemical mediators such as histamines are released, contributing further to inflammation and puffiness alongside the crimson coloration.
In a cruel twist, some firefighters reported feeling temporarily better after reaching the hospital. Rather than reassurance, that brief improvement could align with a dangerous pattern seen after extreme exposures.
Sometimes called the ‘walking ghost’ phase, this fleeting calm can occur while profound internal damage continues unseen. As irradiated skin and underlying layers fail, the body may be unable to replace them with new cells.
With critical regenerative layers destroyed, tissue can begin to slough away, and internal organs may progressively fail. For many of those heavily exposed in the first response, care was limited to what could be offered as their condition worsened.
Official records list 31 deaths in the immediate aftermath of Reactor 4’s explosion, including two plant workers and multiple firefighters. The UN has estimated that 50 deaths can be directly attributed to the disaster.
But the broader human cost extends far beyond those early figures.
The World Nuclear Association has estimated that roughly 200,000 people across the Soviet Union participated in recovery and cleanup efforts in 1986 and 1987. Many were exposed to elevated radiation—averaging around 100 millisieverts (mSv)—a dose that can increase long-term cancer risk, particularly across large populations.
Determining an exact death toll tied to radiation exposure has long been complicated by gaps in baseline public-health data and differing methodologies. In 2005, the UN projected that around 4,000 people could eventually die as a result of radiation exposure linked to the accident.
Beyond premature deaths, researchers and observers have reported increased health problems in contaminated regions, including concerns about birth outcomes in areas that received heavy fallout.
Verywell Health reports that some studies noted a 200% increase in congenital deformities in certain high-fallout areas of Belarus, along with higher reported rates of cancer, stroke, depression and dementia among the so-called “children of Chernobyl.”
Valery Khodemchuk is believed to have been the only person killed instantly at the moment Reactor 4 exploded.
An engineer working as a pump operator, he had been positioned near the reactor as the test was underway. After the explosion and the force that tore through the structure—including the destruction associated with the massive roof components—he was presumed to have died immediately.
Decades later, his remains were never recovered and are thought to be permanently entombed within the debris around Reactor 4.
The firefighters who responded at the destroyed Reactor 4 building were exposed to extraordinarily high radiation levels while attempting to contain multiple fires and limit further catastrophe.
Some estimates place exposures in the range of up to 20,000 mGy or 20 Sieverts—figures sometimes compared to tens or even hundreds of thousands of chest X-rays. Many developed acute radiation syndrome (ARS), with symptoms including vomiting, severe illness, and skin damage, and several died soon after.
Among them was 25-year-old firefighter Vasily Ignatenko. His wife later described the swelling after his death, saying even dressing his body became impossible.
“They had to cut up the formal wear, too, because they couldn’t get it on him, there wasn’t a whole body to put it on,” she said, according to Svetlana Alexievich’s 1997 book, Voices from Chernobyl: The Oral History of a Nuclear Disaster.
Because the bodies of those who died soon after exposure could remain radioactive, burials were handled with additional containment measures, including zinc and concrete, to reduce risk to others.
After Pripyat was evacuated, countless pets—especially dogs and cats—were left behind in the rush to depart.
In the following period, Soviet soldiers shot many of the abandoned animals amid fears their fur carried contamination. Even so, it is thought some dogs survived by hiding and later reproducing, leading to populations that still exist in the Exclusion Zone today.
The University of Cambridge says there are around 500 dogs in the Zone, and that they are supported by the Clean Futures Fund (CFF), a US-based non-governmental organisation that monitors health and manages numbers through spay/neuter work.
In the wider ecosystem, the long-term picture has been surprising. Despite persistent contamination, wildlife populations have rebounded across many parts of the Exclusion Zone over the decades.
Large mammals—including brown bears, moose, European bison and wolves—have been documented returning in significant numbers, suggesting that the removal of human activity has played a major role in reshaping the landscape.
Evolutionary biologist Germán Orizaola, who has studied radiation’s effects in the Chernobyl area since 2016, told the BBC that the absence of people may be a key factor in why wildlife and habitats have flourished in many locations.