Any radioactivity at Magnuson Park would come from radium paint that was used on aircraft instruments to make them glow in the dark. Radium paint was used in two places: a painting room on the second floor of a shed attached to Building 27 and an instrument-repair room on the second floor of Building 2.
How people are exposed to radium
Radon gas is given off by radium and is the most common way that people are exposed to this kind of contamination. Radon is measured as picocuries - or pCi - per liter of sampled air. Radon is detected with a device that samples air.
Gamma exposure to radium is detected with an instrument that most people would know as a Geiger counter. Gamma is measured in units of rem, or microR (also uR) per hour - which equals one millionth of a rem.
Inhaling or swallowing radium - this is something that is very rare.
What we've tested for at Magnuson Park
Radon - We tested the air inside Buildings 2, 27, and 30 at Magnuson Park for radon. The EPA standard for radon cleanup is 4.0 picocuries per liter of air. We found that all readings were below 0.3 picocuries, which is the minimum detection limit.
Gamma radiation - We surveyed several locations around Buildings 2 and 27 in April and June 2013. We found levels similar to "background" radiation that is normally present in the Seattle area.
Neighborhood surveys: We also surveyed several locations in the surrounding neighborhood, and farther away from the Sand Point area including Woodland Park, Queen Anne, Pike Place Market Park, and Safeco Field. All surveyed areas found no unusual levels of radioactivity, and were in the same range as what was found in the Sand Point neighborhood.
Gamma radiation in Seattle: In July 2011, an extensive radiological study was conducted throughout King and Pierce counties, using a helicopter with very sensitive detectors. The levels found in 2011 are even lower than the surveys we conducted in 2013, and show the entire Sand Point area at about 3 microR per hour. The complete Aerial Radiation Survey can be viewed on this website.