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

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.

Stone, brick and adobe have natural radioisotopes in them.

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.

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.

Uranium is often added to these dental products to increase whiteness and florescence.

30,000 feet above the ground you're closer to the ionizing radiation (high-energy gammas well as particles) from the sun.

Its granite walls have a high uranium content.

This is the world's most radioactive food due to high radium concentrations 1000-times that of average foods.

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.