The actual radiation levels at Chernobyl varied significantly depending on the location and the time after the disaster. Immediately after the explosion on April 26, 1986, radiation levels in the vicinity of the reactor were extremely high. Initial readings taken just outside the plant recorded radiation levels exceeding 300 roentgens per hour, which could be lethal within minutes to anyone exposed without proper protection.
In the days following the explosion, the fallout spread across large areas, affecting not just Chernobyl itself but also parts of Europe. Remote areas saw varying levels of contamination, with certain places having significantly different readings due to wind direction and rainfall patterns that deposited radioactive particles.
In the long-term, the radiation levels in the Exclusion Zone, which surrounds the reactor, have decreased. In many areas, levels dropped to relatively safer measurements, often within the range of 0.1 to 20 microsieverts per hour, as the most harmful isotopes decayed over time. However, certain hotspots, particularly around the reactor and in some contaminated forests, still remain hazardous with higher levels of radiation.
In summary, while the initial radiation levels immediately after the disaster were catastrophic, ongoing monitoring and natural decay have led to a significant reduction in radiation over the years, although some areas remain dangerous. Understanding these levels is crucial for assessing the continuing risks and impacts on health and the environment.