Ongoing radiation monitoring performed by the Minnesota Department of Health has found trace amounts of radiation that likely came from Japan, according to an MDH report.

Discovered from samples taken in St. Paul, the radiation from Japan is “thousands of times less than normal background radiation and well below levels that would be of health concern,” according to the report.

Radiation levels measured on March 29 clocked in at .011 millirem per year.

“The exposure level at which we would begin to have concerns for human health is 10,000 millirem,” Sherrie Flaherty, radiation control supervisor for MDH, said in the report.

MDH performs radiation monitoring weekly in St. Paul, and once every two weeks at each of Minnesota’s two nuclear power plants: Monticello Nuclear Power Generating Plant outside of Monticello and Prairie Island Nuclear Generating Plant outside of Red Wing. Both plants are owned and operated by Xcel Energy.

The 9.0 magnitude earthquake and subsequent tsunami that struck Japan’s east coast March 11 severely damaged several reactors in the Fukushima Daiichi nuclear power plant. Radiation has been leaking from theplant over the past several weeks.

Escaped radiation from Japan was detected in Hawaii on March 22, according to the Environmental Protection Agency’s monitoring.

MDH officials said they will continue to monitor radiation levels throughout Minnesota, but expect the increase to disappear in four to six weeks.