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.
Some scientists believe that radon dissolved in the blood may cause additional diseases beside lung cancer. In addition to the gas, one-third of the inhaled radon decay particles also pass through the lungs into the blood stream and then, get trapped. As we breathe in through the skin, the air also carries radon gas.