An exclusion zone is an area where human access is restricted or prohibited, typically because of a nuclear disaster. The most famous is the Chernobyl Exclusion Zone in Ukraine, a 30-kilometer radius around the destroyed nuclear power plant that has been largely uninhabited since 1986. Fukushima, Japan established a similar zone after its 2011 nuclear accident. The term also appears in water chemistry, where it describes something entirely different.
The Chernobyl Exclusion Zone
After the Chernobyl reactor explosion on April 26, 1986, Soviet authorities evacuated roughly 350,000 people and drew a 30-kilometer circle around the plant. That circle became the exclusion zone, and it remains essentially uninhabited nearly four decades later. The contamination itself didn’t respect neat boundaries. Some 150,000 square kilometers across Belarus, Russia, and Ukraine were affected, with radioactive material spreading as far as 500 kilometers north of the plant site.
The zone isn’t uniformly dangerous. Gamma radiation levels measured inside it range from 0.06 to about 100 microsieverts per hour, depending on exact location. To put that in perspective, normal background radiation in an uncontaminated country like Germany sits between 0.06 and 0.2 microsieverts per hour. So some spots in the exclusion zone are no more radioactive than a German park. Others are intensely contaminated: at the worst locations, staying outdoors permanently would push someone past the annual occupational radiation limit for German workers (20 millisieverts) in just eight days.
People Who Stayed Behind
Not everyone left. A small group of residents, mostly elderly, returned to their homes inside the zone shortly after evacuation. Known as “samosely” (self-settlers), their numbers fluctuated between 150 and 2,000 in the years after the disaster. By 2021, only 101 remained. They were predominantly women, mostly elderly or very old, and largely single or widowed.
Decades of low-dose radiation exposure took a measurable toll. Medical studies found higher rates of cerebrovascular disease, thyroid problems, immune system abnormalities, and organic brain damage among the self-settlers compared to the general population. Cardiovascular disease was the leading cause of death. Researchers also documented significant mental health deterioration, primarily borderline psychiatric disorders. The mortality rate among self-settlers climbed from 20 per 1,000 in 1993-1994 to 50 per 1,000 by 1995-1997, largely driven by deaths among those over 80.
Wildlife Inside the Zone
With humans gone, the exclusion zone became an accidental nature reserve. Long-term census data show that elk, roe deer, red deer, and wild boar populations inside the zone now match those of four uncontaminated nature reserves in the surrounding region. Wolves have done even better: their population density inside the exclusion zone is more than seven times higher than in comparable protected areas outside it. The absence of farming, hunting, and development appears to benefit wildlife more than chronic radiation exposure harms it, at least at the population level.
New Uses for Contaminated Land
Because the land can’t be used for agriculture or housing, governments and private companies have explored alternative uses. Two Chinese firms began constructing a one-gigawatt solar power plant south of Chernobyl, and a German renewables company launched its own solar project in the area. Dozens of smaller investors followed with additional solar installations nearby. The logic is straightforward: the land is flat, empty, already connected to the electrical grid through the old power plant infrastructure, and too contaminated for most other purposes.
The Fukushima Exclusion Zone
Japan created its own version after the Fukushima Daiichi meltdown in March 2011. The initial evacuation covered a 20-kilometer radius around the plant. Within weeks, the government layered additional designations on top. Areas between 20 and 30 kilometers were classified as “Evacuation-Prepared Areas in Case of Emergency.” Zones where annual radiation doses were projected to exceed 20 millisieverts became “Deliberate Evacuation Areas.” By June 2011, the government also flagged individual hotspots outside these zones where decontamination would be difficult.
Unlike Chernobyl, Japan has actively worked to reopen evacuated areas. The requirement for lifting evacuation orders is straightforward: estimated annual doses, based on ambient radiation measurements, must fall to 20 millisieverts or below. Several towns have been reopened, though many former residents have chosen not to return.
Exclusion Zones in Water Science
The term “exclusion zone” also shows up in a completely different context: water chemistry. When water sits against a smooth, water-attracting surface (like certain gels or biological membranes), a thin layer forms where dissolved particles and microspheres are pushed away, or “excluded.” This layer, sometimes called EZ water, has unusual properties. It carries a negative electrical charge (around -120 to -200 millivolts compared to the bulk water beyond it), has a higher density, and bends light differently than regular water.
Researcher Gerald Pollack proposed that this layer represents a “fourth phase” of water, structured in hexagonal sheets with hydrogen atoms sitting directly between oxygen atoms. The idea remains controversial. While the exclusion effect itself has been repeatedly demonstrated in labs, the explanation for why it happens is still debated. Some researchers attribute it to the electric field created by aligned hydrogen bonds at the surface, which may influence several layers of water molecules outward.