The purpose of the study was to identify the costs and to assess the economic impact of controlling air pollution from gray iron foundries. Two principal considerations commend the gray iron foundry industry to this type of study. First, the industry is an important source of particulate pollution in most urban metropolitan areas (170,000 tons in 1968). Second, the industry includes a large number of small establishments that may find it difficult to finance the purchase and operation of pollution control equipment. Approximately a third of all companies in this industry employ less than 20 employees. Pollution control costs are examined for the various types of systems commonly applied to reduce furnace emissions. Factors that may influence control costs are tested between the different types of control systems and within types of a systems. Costs of control are measured against the economic strength of the industry and against the financial condition of firms in the industry. Two types of data were collected, individual company data and aggregated industry data. All the known producers of gray iron were surveyed by mail in 1968 to determine which ones had installed pollution control equipment, the types of equipment, and the costs.