[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 \left ( \frac{34\ eV}{Ion}\right ) \times \left ( \frac{ion}{1.610*10^{-19}\ C}\right ) \times \left ( \frac{1.6022*10^{-19}\ J}{eV}\right )[/math]
[math] 1\ R = 0.0087295\frac{J}{Kg} [/math]
[math] 1 \ R = 0.0087295\frac{J}{Kg} \times \left ( \frac{100\ Rad}{1 \frac{J}{Kg}}\right )[/math]
[math] 1\ R = 0.87295\ Rad [/math]
[math] 1.14554\ R = 1\ Rad [/math]
[math] 115 \approx 100\ Rad [/math]