An on-stack transmissometer system, that is designed to provide a precision measurement of the opacity of visible emissions, is described. The sources of error in opacity measurements with regard to recent Environmental Protection Agency emission monitoring requirements and planned specifications are discussed. (Author/BT)

Achievement of air quality goals requires careful consideration of alternative control strategies in view of national concerns with energy and the economy. Three strategies which might be used by coal fired steam electric plants to achieve ambient air quality standards for sulfur dioxide have been compared and the analysis presented. (Author/BT)

This study relates sulfur dioxide levels with material damage in heavily populated or polluted areas. Estimates of loss were determined from increased maintenance and replacement costs. The data indicate a decrease in losses during the past five years probably due to decline in pollution levels established by air quality standards. (MR)