This book presents working principles for assessing the relative importance of anthropogenic emission sources that contribute to haze in U. S. national parks and wilderness areas and discusses various alternative source control methods. Haze in the Grand Canyon evaluates and recommends strategies for improving critical scientific and technical gaps in the information and databases on haze. It examines such topics as methods for determining individual source contributions, regional and seasonal factors that affect haze, strategies for improving air quality models, the interactive role of photochemical exodants, and scientific and technological considerations in choosing emission control measures.