Fluorescence in damp air and comments on the radiative life time
  Photon yields in damp air excited by an electron using a Sr90 $\beta$ source are compared withthose in dry air. Water vapors considerably reduce the yields, however, a further study is needed to evaluate the effects on the energy estimation of ultrahigh-energy cosmic rays. The relation of fluorescence efficiency to the life time of de-excitation by radiation is discussed. 
N. Sakaki, K. Kobayakawa, M. Nagano and Y. Watanabe