Fluoride is an important pollutant emitted into the air predominantly from phosphate fertilizer and Al reduction processes. A widely used analytical method for determining fluoride concentration in stack emission samples is the SPADNS-Zirconium Lake technique. Although this method is generally regarded as accurate and sensitive, it is time consuming, requiring a sulfuric acid or perchloric acid distillation step to remove interferences. The specific ion electrode (SIE) has gained wide acceptance for the determination of soluble fluoride in ambient air particulate matter. The SIE method offers significant advantages over the SPADNS method by virtue of its simplicity, high precision and speed. The application of the fluoride SIE to emission sample analysis has been limited because it responds to interfering ions and may not provide data that are comparable to the SPADNS method. This report describes the results of a study to assess the equivalence of the SIE and SPADNS methods for the determination of soluble fluoride in emission samples from phosphate fertilizer and A1 reduction plants.