Similar words: head-on, head on, lead on, adonis, prima donna, paradox, desperado, paradoxical. Meaning: ['reɪdɑn /-dɒn] 
n. a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health.
n. a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health. 
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61. In order to deal with the sideward influences, "X" interferences and other linear interferences, the Radon transform can be used to process the ground penetrating radar (GPR) profile.
62. The anomalies are analyzed with sliding mean and secondary function method. The results show that the medium term anomalies of radon are corresponding well with the two events.
63. A scintillation cell is a detector which is often used in measuring radon.
64. When radon gas emitted as springs, very quickly, a phenomenon opal.
65. It was successfully used to automatically determine the concentrations of radon and thoron daughters in air.
66. A radioactive, inert, gaseous isotope of radon a half - life of 3.92 seconds.
67. Any of the six chemical elements that make up the rightmost group of the periodic table as usually arranged: helium, neon, argon, krypton, xenon, and radon.
68. Radon concentration in groundwater was measured at 18 points including two continuous recording stations.
69. The radon exhalation rate is used as the basic factor of radon geological potential.
70. The authors also studied the continuous self-recording technique by using the ionization method to measure the Radon gas.
71. The average outdoor radon level varies between 5 and 15 Bq/m3 [Radon radioactivity is measured in Becquerel (Bq).
72. The charcoal coil monitor for radon 222 Rn in air is calculated and analysed.
73. Radon concentration in air is measured by the number of transformations per second in a cubic metre of air (Bq/m3)].
74. Objective Study on radon pollution in tunnel and protection from the radiation.
75. Indoor environment for thousands of varieties of hazardous substances, the most important are : radon, radioelement , formaldehyde, benzene, ammonia, PVC,(http://sentencedict.com/radon.html) nitrogen oxides and carbon oxides.
76. Most countries have adopted an indoor air radon concentration of 200–400 Bq/m3 as a reference level above which mitigation measures should be taken.
77. To improve the detectable limit of radioactive aerosol monitors, it is very important to eliminate the interference of the natural background, i. e. radon and thoron daughter aerosol.
78. Radon is known to be harmful to humans in large quantities.
79. Radon is a gas that comes from the radioactive decay of radium in rocks.