The duration for radiation to clear out after a nuclear event depends on several factors, including:
- Yield of the nuclear weapons: Larger explosions produce more fallout.
- Type of isotopes released: Different radioactive isotopes have varying half-lives. For example, iodine-131 has a short half-life of about 8 days, while cesium-137 has a half-life of about 30 years.
- Weather conditions: Rain can wash away fallout, potentially reducing contamination in some areas.
- Geography and urban density: Fallout distribution is affected by wind patterns and terrain; urban areas may be more contaminated due to the presence of buildings and infrastructure that can trap radioactive particles.
- Cleanup and recovery efforts: Human intervention can accelerate the decontamination process.
In general, areas affected by fallout could remain hazardous for weeks or months, depending on the level of exposure and specific isotopes. Areas impacted by long-lived isotopes could remain dangerous for many years. Full recovery in terms of safety for human habitation might take decades, especially in heavily affected areas.
It's crucial to emphasize that the use of nuclear weapons would have catastrophic humanitarian and environmental consequences, and the focus should be on preventing such a conflict.