An air quality dispersion model, BLP, (Part of the UNAMAP version 4 collection) was developed to simulate the transport and diffusion of effluents from aluminum reduction plants. These plants are complex emission configurations consisting of multiple parallel low-level buoyant line sources interspersed, in most cases, by short point sources. Available air quality models do not adequately describe the dispersion of effluents from aluminum reduction plants or other geometrically similar facilities. A wind tunnel simulation program of two aluminum reduction plants and an SF6 field tracer program at one of these plants was used to obtain data for the development of the model. The model determines plume rise from buoyant line sources and analytically incorporates the effects of multiple lines, wind direction, vertical wind speed shear, and downwash. Plume rise from buoyant point sources also incorporates the effects of vertical wind speed shear and downwash.