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.
A: Some of the symptoms of radon gas exposure include a persistent cough that does not improve, coughing up blood, hoarseness, difficulty breathing, and wheezing. Resembling lung cancer, chest pains and recurring bronchitis or pneumonia are other signs of radon exposure, according to National Radon Defense.