Everyday exposures

Average annual radiation dose is 360 millirems per person. 300 from natural sources.

Sleeping next to someone for 8 hours: 2 mrems

Exposure comes from the naturally radioactive potassium in the other person's body
Coal plant, living within 50 miles: .03 mrem
There is much thorium and uranium in coal. Living within 50 miles of a nuclear power plant adds .009 mrem of exposure. Both figures are considered extremely low levels.
Living in a masonry home: 7 mrems
Stone, brick and adobe have natural radioisotopes in them.
Living on the Earth: 200 mrems
We are living in a sea of radon. It is made from the natural decay of uranium and thorium in the soil, left over from the creation of the solar system. Radon is a rare gas that diffuses out of soil and into the air. It contributes more than half of our background exposure.
Smoking: up to 16,000 mrems
The tobacco leaf acts like the absorbing surface of charcoal in a radon test kit. It collects long-lived isotopes of airborne radon, like lead-210 and polonium. Small portions of the lungs can get relatively whopping doses, compared to background levels.
Porcelain teeth or crowns: tenths of a rem
Uranium is often added to these dental products to increase whiteness and florescence.
Air Travel: 1 mrem per 1000 miles
30,000 feet above the ground you're closer to the ionizing radiation (high-energy gammas well as particles) from the sun.
Grand Central Station, NYC: 120 mrem for employees
Its granite walls have a high uranium content.
Brazil Nuts:
This is the world's most radioactive food due to high radium concentrations 1000-times that of average foods.
The US Capitol Building in Washington DC:
This building is so radioactive, due to the high uranium content in its granite walls, it could never be licensed as a nuclear power reactor site.
Sources: Living with Radiation, the First Hundred Years
America the Powerless
Los Alamos Science
Bluebells and Nuclear Energy

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