Radioactive materials were released from the power station following the accident. However, measures including decontamination operations have significantly reduced radiation levels, excluding Difficult-to-Return Zones. According to surveys of ambient dose rates over an 80-kilometer radius around the Fukushima Daiichi Nuclear Power Station, the average dose at a height of 1 meter above the ground has decreased by around 78% compared to the level immediately after the accident and as of September 2019.
What’s more, radiation dose levels will continue to decrease naturally because the ability of radioactive materials to emit radiation gradually decreases as the materials become more stable over time while emitting radiation.

Decontamination has been carried out by the central and local governments since January 2012 in accordance with the law (Act on Special Measures Concerning the Handling of Environment Pollution by Radioactive Materials). As of March 2018, thorough area-wide decontamination work has been completed in 100 municipalities across 8 prefectures, excluding Difficult-to-Return Zones.

For the latest updates on decontamination, visit the Ministry of the Environment’s Environmental Remediation website