The use of action spectra in calculating biologically effective ultraviolet radiation fluence is reviewed. In predicting biological damage due to ozone depletion, the most reliable action spectra are those derived from experiments utilizing polychromatic irradiation filtered by sharp cut‐off UV filters. A new method is presented for optimum estimation of an action spectrum from data obtained in such experiments. Details of the mathematical procedures are discussed, and examples of their use on data from both plant and animal objects are given.

Secondary electron ejection coefficients for rare gas metastable atoms striking a stainless steel surface have been determined using an improved gas cell technique. Data are presented for He(2 1S), He(2 3S), and Ne(3P0,2) atoms, and limitations of this technique are discussed. An alternative method for γ determination is described which utilizes laser induced photoionization rather than chemiionization, and results are presented for He(2 1S) and Xe(3P0).

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A concise stratospheric model has been used in a Monte Carlo analysis of the propagation of reaction rate imprecisions through the calculation of an ozone perturbation due to the addition of chlorine. Two thousand Monte Carlo cases were run in which all 55 reaction rates were varied simultaneously and individually. Excellent convergence was obtained in the output distributions because the model is sensitive to the imprecisions in only about 10 reactions. For a 5.7 ppbv (parts per billion by volume) chlorine perturbation added to a 1.5 ppbv chlorine background the resultant 1σ imprecision in the ozone perturbation is a factor of 1.35 on the high side and 1.69 on the low side. The corresponding 2σ factors are 1.81 and 2.86. Results are also given for the imprecisions, due to reaction rates, in the ambient concentrations of stratospheric species.

Crossed beams studies of chemiionization in thermal energy collisions of helium, neon, argon, and krypton metastable atoms with ground state atoms and molecules (Ar, Kr, Xe, N2, H2, O2, NO, CO, CO2, and N2O) are described. Branching ratios are presented and in some cases absolute total ion production cross sections have been measured.