The regulations implementing the 1977 Clean Air Act Amendments distinguish between thedetectabilityof air pollution‐caused visibility impairment in Class I Parks and Wilderness areas and the adversity of impairment, referring to the effect on the quality of park visitors’ visual experiences. Two lines of environmental perception research have arisen from this distinction, one emphasizing the detectability of visibility impairment, and the other emphasizing the quality of park visitors’ experiences. This study addressed issues relevant to both lines of research. Subjects rated either the “visual air quality”; or “scenic beauty”; of color slides depicting varying levels of atmospheric visibility in Class I scenic vistas under treatment conditions designed to emphasize either the detectability or adversity criteria. Subjects who rated visual air quality for repeated samples of a single vista were most sensitive to changes in atmospheric visibility. Subjects who rated a mixture of different vistas for scenic beauty were least sensitive to visibility changes. Lighting conditions and the composition of the paricular vista being viewed also proved to have substantial influence on perceptual ratings.