Here's an article by a woman who obtained a radiation monitor and noted it's readings at various places she went: http://www.ratical.org/radiation/radMonData.html I have a question about this passage: Why would this clock be so radioactive? I am also baffled by this revelation: Why is it so radioactive in the sky? I started out doing a bit of research into the radioactivity of common food, due to my accidental discovery of the banana equivalent dose. http://en.wikipedia.org/wiki/Banana_equivalent_dose This lead to having to sort out units of radiation: http://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html That site contains the following mysterious comparisons: What's mysterious is why 2 days in Denver should equal a whole year next door to a nuclear power plant. It required looking into. The answer is startling: http://www.theatlantic.com/national...ophe-youve-probably-never-heard-about/261959/ Anyway, I'm not sure why a non-illuminated clock should be so radioactive, nor why the radiation is so extremely high in commercial jets.