Study of the relationship of distant SO2 emissions to Dallas-Fort Worth winter haze

A study was conducted to estimate the changes in winter-time visual air qua lity in Dallas-Fort Worth (DFW) that might occur due to proposed reductions in SO2 emissions at two steam electric generating plants in eastern Texas, each over 100 km from the city. To provide information for designing subse quent investigations, the haze was characterized broadly during the first y ear of the study. Meteorological data acquired then demonstrated that, duri ng haze episodes, emissions from only one of the two plants were likely to be transported directly to DFW. Therefore, the second year of the study was centered on just one of the power plants. Air quality was then characteriz ed within the urban area and at rural locations that would be upwind and do wnwind of the plant during transport to DFW. An instrumented aircraft measu red plume dispersion and the air surrounding the plume on selected days. A mathematical model was used to predict the change that would occur in airbo rne particulate matter concentrations in DFW if SO2 emissions were reduced to reflect the proposed limitations. The contribution of particles in the a tmosphere to light extinction was estimated, and simulated photographs were produced to illustrate the visibility changes. The study concluded that th e proposed emission reductions would, at: most, subtly change perceived win tertime visibility.