This test method is intended for determining the resistance of the color of textiles to the action of ozone in the atmosphere at room temperatures with relative humidities not exceeding 67%. 2. Principle 2.1 A test specimen and a control specimen are simultaneously exposed to ozone in an atmosphere under ambient temperatures (64-82F) and relative humidities not exceeding 67%, until the control specimen shows a color change corresponding to that of a standard of fading. This exposure period constitutes one cycle. The cycle is repeated (1) until the specimen shows a definite color change or (2) for a prescribed number of cycles.