Radioactive iodine has been found in the air across the nation.

The Korea Institute of Nuclear Safety said on Tuesday that the radioactive substance was detected in air samples collected from all monitoring stations located in the nation’s 12 regions, with the highest level at 0.758 becquerels per cubic meter.

Radioactive cesium was also detected in five areas, including Seoul and Jeju Island.

The figures are based on the analysis of air measured between 10 a.m. on Sunday and 10 a.m. on Monday.

In addition, the institute collected and tested rainwater taken from Jeju and Gwangju, where it rained on Monday morning. Rainwater from Jeju was found to contain 0.357 becquerels of radioactive iodine per liter.

The institute said that the levels of radioactive substances found in air and rainwater are negligible, with little impact on the human body or the environment.