Exposure to radon gas, which is present in the environment naturally, constitutes over half the radiation dose received by the general public annually. At present, the most widely used method of measuring radon concentration levels throughout the world, both in dwellings and in the field, is by etched track detectors — also known as Solid State Nuclear Detectors (SSNTDs). Although this is not only the most widely used method but is also the simplest and the cheapest, yet there is at present no book available on the market globally, devoted exclusively or largely to the methodology of, and dealing with the results obtained by, the SSNTD technique. The present book fills this important gap in the coverage of radon measurements. Individual chapters of the book are contributed by some of the most prominent and active research workers in the world in the SSNTD discipline as well as in the field of radon measurements. A detailed breakdown of the contents of the book is shown below together with the name(s) of the author(s) of each chapter.