This International Standard describes the equipment, methods and procedures for generating a known ozone exposure and the subsequent measurement and quantification of the amount of change produced within both digitally printed hardcopy images and traditional analogue photographic colour print images due to that exposure. The test method described in this International Standard uses increased levels of ozone to achieve an accelerated test. If the principal “gas fading” mechanism for a system is not ozone, this method might not be suitable and might give misleading results as to resistance of the test image to polluted air.