The land use and land cover information developed by the U.S. Geological Survey in the Central Atlantic Regional Ecological Test Site project has been proven useful when used in an improved technique for estimating emissions, diffusion, and impact patterns of sulfur dioxide (S02) and particulate matter. Implementation of plans to control air quality requires land use and land cover information, which, until this time, has been inadequate. The land use and land cover data were used in updating information on the sources of point and area emissions of S02 and particulate matter affecting the Norfolk-Portsmouth area of Virginia for the 1971-72 winter (Dec.-Jan.-Feb.) and the annual 1972 period, and for a future annual period-1985. This emission information is used as input to the Air Quality Display Model of the Environmental Protection Agency to obtain diffusion and impact patterns for the three periods previously mentioned. The results are: (1) During the 1971-72 winter, estimated S02 amounts over an area with southwest-northeast axis in the central section of Norfolk exceeded both primary and secondary levels, (2) future annual levels of S02, estimated by anticipated residential development and point-source changes, are not expected to cause serious deterioration of the region's present air quality, and (3) for the 1971-72 winter, and annual 1972, period the diffusion results showed that both primary and secondary standards for particulate matter are regularly exceeded in central Norfolk and Portsmouth. In addition, on the basis of current control programs, the 1985 levels of particulate matter are expected to exceed the presently established secondary air-quality standards through central Norfolk and Portsmouth and in certain areas of Virginia Beach. Land use and land cover information can be used to estimate emissions for inputs to diffusion models and to interpret the implications of diffusion patterns for: (1) Implementing various control strategies, (2) selecting sites of air sampling stations, and (3) predicting the effects that proposed changes in land use and land cover might have on emission patterns and air quality.