HELSINKI (AP) — Many Finnish pharmacies ran out of iodine tablets Wednesday, a day after the Nordic country’s health ministry recommended that households buy a single dose in a case of a radiation emergency amid increasing fears of a nuclear event due to Russia’s war in Ukraine.

“An accident at a nuclear power plant could release radioactive iodine into the environment, which could build up in the thyroid gland,” the Finnish Ministry of Social Affairs and Health said Tuesday.

Pharmacies in many locations in Finland reported Wednesday they had run out of iodine tablets as citizens rushed to purchase the medicine. Drug wholesale also said their were stockpiles emptied out.

The ministry said the iodine tablet recommendation is limited to those aged 3-40 because of the potential risks that radiation exposure poses to that age group.

The ministry didn’t mention Russia’s war in Ukraine and didn’t disclose where such nuclear accidents could potentially take place. It only said it had revised guidelines on the use of iodine tablets to match the latest iodine recommendations set by the World Health Organization.

However, Petteri Tiippana, director general of the Radiation and Nuclear Safety Authority of Finland, told the Finnish newspaper Ilta-Sanomat there was a link between the update and the situation in Ukraine.

“Yes, the war in Ukraine has influenced the updating of the instructions,” Tiippana told the newspaper. ”People must have up-to-date instructions should such a need arise.”

In a case of a radiation emergency, sheltering indoors is the main way for people to protect themselves from hazardous radiation, the Finnish health ministry stressed.

Follow the AP’s coverage of the war at https://apnews.com/hub/russia-ukraine