Maps, compasses, astrolabes, and calipers are among the early tools used by ocean navigators. In the modern era, these tools have been largely replaced by electronic and technological equivalents. Despite these early beginnings, it would take many centuries before global navigation at sea became possible.
Harmful Effects of Radon. 1  Radon is the second leading cause of lung cancer (diagram to the right) and a serious public health concern. 2  The primary adverse health effect associated with chronic exposure to radon is lung cancer (typically bronchogenic): -squamous cell carcinoma.
Radon is a radioactive gas that causes cancer. Radon is found in rock, soil, water, some building materials, and natural gas. You can't see, taste, or smell it. Any home, school, office, or other building can have high levels of radon. Radon is found in new and old buildings.