Japan’s damaged nuclear plant in Fukushima has been emitting radioactive iodine and caesium at levels approaching those seen in the aftermath of the Chernobyl accident in 1986, says Gerhard Wotawa of Austria’s Central Institute for Meteorology and Geodynamics in Vienna.

Austrian researchers have used a worldwide network of radiation detectors — designed to spot clandestine nuclear bomb tests — to show that iodine-131 is being released at daily levels 73 percent of those seen after the 1986 disaster. The daily amount of caesium-137 released from Fukushima Daiichi is around 60 percent of the amount released from Chernobyl.

Children who ingest iodine-131 can develop thyroid cancer 10 or more. Caesium-137 lingers in the environment because of its long half-life. Researchers are divided over how much damage environmental exposure to low doses has done since Chernobyl — it could yet cause new cases of cancer.