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.
Radon for Children. Harmful Effects of Radon. Radon is the second leading cause of lung cancer (diagram to the right) and a serious public health concern. The primary adverse health effect associated with chronic exposure to radon is lung cancer (typically bronchogenic): -squamous cell carcinoma. -small cell carcinoma.
Radon is a radioactive gas that occurs naturally when the uranium in soil and rock breaks down. It is invisible, odourless and tasteless. When radon is released from the ground into the outdoor air, it is diluted and is not a concern.he risk of cancer depends on the level of radon and how long a person is exposed to those levels. Exposure to radon and tobacco use together can significantly increase your risk of lung cancer. For example, if you are a lifelong smoker your risk of getting lung cancer is 1 in 10.