[math] 100\ Rad = 1 \frac{J}{Kg} [/math]
[math] 1\ R = 2.58*10^{-4}\frac{C}{Kg} [/math]
[math] \text{Average Ionization Energy for Air} = 34\frac{eV}{Ion} [/math]
[math] 1\ eV = 1.6022*10^{-19}\ J [/math]
[math] 1.610*10^{-19}\frac{C}{Ion} [/math]
[math] 1\ R = \left ( \frac{ 2.58*10^{-4}\ C}{Kg} \right ) \times \frac{34\ eV}{Ion} * \frac{ion}{1.610*10^{-19}\ C} * \frac{1.6022*10^{-19}\ J}{eV}[/math]
[math] 1\ R = 0.0087295\frac{J}{Kg} [/math]
[math] 1 \ R = 0.0087295\frac{J}{Kg} * \frac{100\ Rad}{1 \frac{J}{Kg}} [/math]
[math] 1\ R = 0.087295\ Rad [/math]
[math] 1.14554\ R = 1\ Rad [/math]
[math] 114 \approx 100\ Rad [/math]