Gas fading is a unique phenomenon of inkjet porous media, which is usually evaluated by accelerated ozone fading tests. We studied the influences of various test conditions, such as ozone concentration, relative humidity and circulated air in a test chamber. As a result, some media-printer combinations showed reciprocity failure between ozone concentration and time of exposure. This reciprocity failure was remarkable at low relative humidity. The influence of relative humidity was different with each media-printer combination. And we found that some media-printer combinations were affected by circulated air in a test chamber.