UW physicists monitoring for radiation in Seattle


by MEG COYLE / KING 5 News

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Posted on March 30, 2011 at 5:44 PM

SEATTLE -- University of Washington physicists recently detected low-level radiation in the air in Western Washington.  They started tracking it not because they feared for public health, they feared for their experiments, many of which are highly sensitive to radiation.

But what they found even surprised them.

"Personally, I did not imagine we would see anything at all, actually," admits Professor Hamish Robertson, a UW Physics Professor and Director of the Center for Experimental Nuclear Physics and Astrophysics.

UW physicists are testing air filters on the ventilation intake of the other physics building on campus.

"The airflow rate is very high there, so we take large samples of air," Robertson said.

They then crush the air filter in a 40-ton press and place it in a lead brick-protected "oven" of sorts. The gamma rays go to work and the scientists analyze them.

The results are almost instant.

"Just a couple of minutes into the counting you start to see some of the counts cluster… " said Andreas Knecht, PhD.

It is evidence of nuclear fission. But, not evidence of an impending health concern, Robertson said.  The levels, they insist, are simply miniscule.

"You're exposed to activity every minute of every day, which is thousands of times more than what we've seen from the reactor," said Robertson.

Robertson says the levels of radioactivity are expected to gradually drop off.  That's because the elements present have a relatively short half-life.

Only three products, including iodine 131, were present in the air samples out of dozens of elements.  Robertson says that could mean the material that arrived in Seattle came from the evaporation of contaminated steam released from the reactors in Japan.

So, if it's in the air, is it in all the rain, too?  Robertson does acknowledge radiation can be carried in rainwater as well but says as long as it's not a concern in the air, it's not a concern in the water.