Special Report No. 76-07: A Summary of Analytical Procedures Currently Employed in Ambient Sulfate Aerosol Investigations

The already recognized difference in pulmonary response caused by different sulfate species emphasizes the need for species-specific analysis of sulfate aerosols in the ambient air. While sulfuric acid mist and certain other heavy metal and acid sulfate aerosols are known respiratory irritants, the methods for measurement of ambient sulfate aerosols to this point have generally measured total-water soluble sulfates. The attached Special Report prepared by Dr. Robert P. Fisher, Research Chemist, Southern Regional Center, presents a summary of the state of the art of ambient sulfate aerosol analytical procedures. This report expands on the limitations of the total water soluble sulfate analysis used to this time in adequately defining the level of specific sulfate aerosols in ambient air. The report then proceeds to outline the sulfate aerosol analytical procedures which are under investigation in a wide array of studies, most of which are supported by EPA. The sampling and analytical methods which are sulfate species- specific are not simple. They are sufficiently well advanced, however, that should the need arise today for distinguishing between soluble sulfate and strong acid aerosols, such as might be the case in the vicinity of kraft mills, meaningful studies could be conducted, The progress being made in sample collection and analysis suggests that programs whose delay of another year can be tolerated will have the advantage of methods and instrumentation which are more thoroughly investigated.