From RFE/RL: https://www.rferl.org/a/russian-weather-agency-says-radioactive-isotopes-found-after-accident/30129439.html
“Russian Weather Agency Says Radioactive Isotopes Found After Accident August 26, 2019 10:19 GMT, By RFE/RL
Russia’s state meteorological agency says it found several radioactive isotopes in samples it took following a recent accident at a northern military base during a weapons test. Rosgidromet said in a statement on August 26 that it found strontium, barium and lanthanum in test samples in nearby Severodvinsk, but added that there was no danger to the public at large.
The August 8 accident in the northern Russian region of Arkhangelsk, which killed at least five people and injured several others, raised concerns of atmospheric contamination after emergency officials reported a spike in background radiation levels. “I’m absolutely positive, and I have every reason to affirm the absence of any factors endangering the health and lives of people in the Arkhangelsk region, both on August 8 and at the present,” Interfax quoted regional Governor Igor Orlov as saying on August 26 after the Rosgidromet statement was released. “There are no residents of the region or medical professionals who have been or are exposed as a result of the incident,” Orlov added. Some U.S. officials have said they believe radioactive elements were involved in the accident, and many analysts have focused attention on a nuclear-powered cruise missile that President Vladimir Putin announced was under development last year.
The White Sea bay where both the shipbuilding port and the regional capital, Arkhangelsk, are located were ordered closed for swimming and fishing due to the presence of toxic rocket fuel.
Following the accident, there were reports of panic buying of iodine drops in the shipbuilding town of Severodvinsk. Iodine is often taken to protect the thyroid gland from some types of radiation.
Rosgidromet said a cloud of inert radioactive gases formed as a result of a decay of the isotopes and was the cause of the brief spike in radiation in Severodvinsk.
The isotopes were Strontium-91, Barium-139, Barium-140, and Lanthanum-140, which have half-lives of 9.3 hours, 83 minutes, 12.8 days, and 40 hours respectively, it said.
With reporting by Interfax
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These are the isotopes admitted to. Furthermore, this is half lives, so that the 12.8 days will remain radioactive for many months.