In March, a small amount of radioactive sulfur from the Fukushima Dai-ichi nuclear plant was detected as far as in California, but researchers now say that the amount was not dangerous to health.

According to Mark Thiemens, a professor of chemistry at the University California, San Diego, although the amount was above the normal level, it was still small and "almost nothing."

"It took me three years to figure out the chemistry, to be able to measure things that low," he told USA Today.

The incident fascinated scientists because while reactors don't make sulfur, the radioactive isotopes of sulfur were found to be originated from the reactors of the damaged Fukushima Daiichi nuclear plant.

Following the burst, the water pumps to cool reactors at the Japanese nuclear plant were damaged, which led to the heating up of the reactors. At that point of time, the operators of the plant didn't have any other choice but to use sea water.

As a result, some of the chlorine atoms in the sea water captured neutrons from the reactor and produced radioactive sulfur called Sulfur 35. There were 1,500 atoms of Sulfur 35 per square meter in the air in La Jolla, Calif., scientists said.

Thiemens and his team were measuring the levels of sulfur-35 as part of climate research. They collected readings between March 22 and April 1. The radioactive sulfur took about seven days to cross the Pacifc Ocean, Thiemens said.

A few weeks after the Fukushima Daiichi nuclear plant got damaged on the March 11 tsunami, low amounts of radioactive iodine were detected in milk samples in different cities around the U.S. including California, Colorado, Connecticut and Massachusetts.

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