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 exposure is, after tobacco smoke, the leading environmental cause of lung cancer death (Copes 2007; EPA 2009a). Thus for nonsmokers, radon exposure is the leading cause of lung cancer death, period (EPA 2009b).The risk of lung cancer from radon exposure is estimated at between 10 to 20 times greater for persons who smoke cigarettes as compared with those who have never smoked.hus for nonsmokers, radon exposure is the leading cause of lung cancer death, period (EPA 2009b). The risk of lung cancer from radon exposure is estimated at between 10 to 20 times greater for persons who smoke cigarettes as compared with those who have never smoked.