ANSI Standard IT9.9-1996 is commonly recommended for predicting dark storage print life for color photographic materials. This methodology focuses primarily on measurement of density changes that occur as a function of temperature at 50% ± 3% relative humidity (Arrhenius methodology). An additional factor in the dark stability of inkjet photographic prints is the presence of ozone. Current practical tests utilize a relatively high concentration (5 ppm) of ozone for short periods of time at ambient temperatures to predict what might occur for longer exposures at lower concentrations. However, ambient ozone levels are typically well under 0.1 ppm (100 ppb). The objective of this paper is to explore the effect of ozone concentration on inkjet photographic prints produced with commercially available desktop inkjet printers. The primary focus will be on current dye-based inks printed onto both porous and non-porous photo-quality papers. We will examine the reciprocity relationship between ozone concentration and the duration of exposure to ozone.