The event was not an isolated incident; there had been a series of radioactive discharges from the piles in the years leading up to the accident. In the Spring of 1957, only months before the fire, there was a leak of radioactive material in which dangerous strontium-90 isotopes were released into the environment. Like the later fire, this incident was also covered up by the British government. Later studies on the release of radioactive material as a result of the Windscale fire revealed that much of the contamination had resulted from such radiation leaks before the fire.