FIG. 7.

Increase in biologically effective UV irradiance (biologically effective dose) with decreasing simulated ozone column thickness as measured by the spore biofilm technique in a space experiment. (A) Extraterrestrial solar spectral irradiances filtered through a quartz (7 mm) plate (H) or additionally through cutoff filters simulating different ozone column thicknesses with a progressive simulated ozone depletion from curves A to G. (B) Biofilm data of biologically effective solar irradiance for the different ozone column thicknesses, given in Dobson units (DU) (A to G), the extraterrestrial UV spectrum (H), and ground control (GC, Cologne). The dashed line shows the corresponding curve for DNA damage calculated by Madronich (95). (Data are modified from reference 75.)