The main risk inside the storage facility is the chemical toxicity of uranium hexafluoride gas and fluoride compounds generated in contact with water. The radiological risk from enriched uranium at Natanz is likely to be much smaller than the chemical toxicity from the fluorine.

The United States has joined Israel in its attacks on Iran’s nuclear program. The U.N.'s atomic watchdog and other experts say radiological contamination is likely inside a key uranium enrichment site at Natanz that was badly damaged by Israel and then hit by U.

Early on Sunday, the United States bombed three Iranian nuclear sites after more than a week of Israeli strikes on Tehran’s military and nuclear sites, stoking concerns about radiation leaks and contamination in Iran and neighbouring countries in the region.