2/13/2012 ? Alert ! 110 CPM in the SNOW - St. Louis, Missouri ? AVOID EXPOSURE ?

Radon is responsible for the most background dose

Radon is responsible for the most background dose

Courtesy of the Health Physics Society at the University of Michigan:

http://www.umich.edu/~radinfo/introduction/radrus.htm

Radon is 55% of average background dose

Snow can be naturally radioactive

Just like rain, snow can be radioactive due to naturally-occurring radon gas. This was shown recently in a blog post on Safecast.org for a snowfall in Japan (thanks, BC!).

An easy way to show that a sample contains radon decay products is to take data periodically for a couple hours. The activity should decay away with a half-life of around 30 minutes. This has been demonstrated by us with a swipe sample after it rained and by forum participant James who measured his home air filter with a Geiger counter and we fit his data with a radon daughter decay curve.

Mark [BRAWM Team Member]