Alkalinity can affect the performance of air sampling filters because alkaline sites on the filter can react with SO2, HNO3, and other acid gases to form sulfates and nitrates. These sulfates and nitrates cannot be distinguished from participate sulfate and nitrate collected by the filters. In turn, the total particulate weight, sulfate content, and nitrate content determined are falsely high In proportion to filter alkalinity. Thus, alkalinities of older filters have been measured to determine appropriate correction factors for previously obtained particulate data. Alkalinity of new filters is also tested for compliance with procurement specifications. At laboratories measuring alkalinity, a reproduclbillty problem has been observed In using ASTM Method D 202, which was Intended for analysis of electrical insulating paper and not glass fiber or quartz fiber media. Therefore, we investigated the factors Influencing alkalinity measurements and developed a simple, reproducible method of analysis. The result...