Fact Focus: Israeli strikes on Iran nuclear sites pose limited radiation risks

With Israel intensifying its attacks on Iran's nuclear program, and President Donald Trump hinting the U.S. might join the effort, here is what we know about the radiation threat, and other health risks.

No elevated radiation levels detected yet

Iran enriches uranium at two key sites, Natanz and Fordo.

The Islamic Republic's leaders say their nuclear program is for the peaceful purpose of harnessing atomic energy. But highly enriched uranium — which is radioactive — is used in the manufacture of atomic weapons, and Israel is determined to prevent Iran from having them.

At Natanz, some 220 kilometers (135 miles) southeast of Tehran, uranium had been enriched to up to 60% purity — a mildly radioactive level and a short step away from weapons grade — before Israel destroyed the aboveground part of the facility, according to the U.N.'s nuclear watchdog, the International Atomic Energy Agency.

Another part of the Natanz facility is below ground, and where most of its centrifuges are to protect them from airstrikes. The IAEA said Tuesday it believes that most if not all of these centrifuges were destroyed by an Israeli strike that cut off power to the site. These centrifuges had been enriching up to 5% purity, according to experts.

While radiological and chemical contamination are likely inside Natanz, radiation levels outside the complex remain normal, Rafael Grossi, chief of the IAEA, said during an urgent session of the IAEA board on June 16.

The Fordo nuclear enrichment site is buried deep below a mountain, around 100 kilometers (60 miles) southwest of Tehran, and is close to the Shiite holy city of Qom.

Iran produces most of its near weapons-grade material there — and for that reason it is considered a high-value target for the Israelis. But its location deep underground makes it difficult to attack, which is why the U.S. is considering deploying powerful ''bunker buster'' bombs to destroy Fordo.

Even so, experts said any potential radiation impact from a strike on Fordo is likely to be similar to the impact at Natanz. In short, there would be some chemical hazards on site, and some radiation, but at levels that would be manageable with respiratory devices and other protective gear.

Last week, Israel struck four buildings at the Isfahan nuclear site, among them a uranium conversion facility. The IAEA said there has been no sign of increased radiation at Isfahan, which is roughly 350 kilometers (215 miles) southeast of Tehran.

Risk from uranium is minimal

Even if radiation did leak from either Natanz or Fordo, experts said, the amount would be unlikely to pose a risk to people near the facilities or in the wider region.

''Very little uranium will be released in these kind of attacks,'' said David Albright, a physicist and nuclear weapons expert who founded the Institute for Science and International Security, based in Washington.

Uranium itself is not especially toxic, he said, and is common in parts of the environment. A person standing near an enrichment facility with a leak would probably be exposed to no more radiation than someone who took several trans-Atlantic flights, which receive slightly higher radiation because radiation doses are larger at high altitudes, he said.

In order to become sick, someone would have to ingest large quantities of uranium, Albright said, pointing out that the element can be found naturally in seawater and the earth's crust.

A chemical used in uranium enrichment could be a threat

Rather than radiation, experts said the greater risk from any attack on nuclear enrichment sites might be from fluorine gas.

Fluorine is mixed with a concentrated form of uranium to create uranium hexafluoride, which is then fed into centrifuges. Fluorine is extremely volatile, will quickly corrode and can burn the skin. It is especially deadly if inhaled.

A far greater concern to the public would be if Israel were to attack Iran's only nuclear power plant, said Fabian Hinz of the International Institute of Strategic Studies.

In a nuclear power plant, the reactor core and the spent nuclear fuel are the most radioactive components. Some of it remains dangerous for thousands of years.

The Bushehr power plant is 750 kilometers (465 miles) south of Tehran. But ''it seems very unlikely that the Israelis are going to strike'' Bushehr, Hinz said, because it isn't considered to be part of the Iranian nuclear program geared toward developing weapons.

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Mroue reported from Beirut. Liechtenstein reported from Vienna.

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