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pollutants iith two particle size cutoffs-10 and 15 pm. IPN samples wereanalyzed for 16 metals by X-ray fluorescence. The IPN was terminated last vear: now EPA only gathers informition from NASN samples.
Congress has become increasingly concerned about human exposure to potentially toxic air pollutants. There is already legislation in place that requires EPA to control toxic air pollutants. Some members of Congress feel that EPA has been too slow in acting on these requirements. As a result, EPA is likely to receive more specific congressional direction to list and control pollutants that may be toxic to humans. To be considered toxic, a chemical must not only have the potential to be toxic but must also be present in ambient concentrations that may cause harmful human health effects. Without knowledge of what concentrations currently exist, the existence of detrimental health effects cannot be determined. This raises several questions about the availability and quality of data on potentially hazardous pollutants. There are two major subsets of potentially toxic air pollutants: elemental metals and metal compounds, and organics. Monitoring metals
Elemental metals have been used as a proxy for determining concentrations of metal compounds at about 150 of the National Air Surveillance Network (NASN) sites. Samples are sent every quarter to EPA's Environmental Systems Laboratory and analyzed for about a dozen different metals. Ambient data on metals are also available from EPA's lnhalable Particulate Network (IPN). IPN samples were collected using a dichotomous sampler 0013-936X/83/0916-0529A$01.50/0
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CoUecting data on organics EPA has been investigating several different methods for monitoring organic air pollutants. A Philadelphia site has been used to monitor many organics in different ways. Data collected by the various methods will be compared for their accuracy and reproducibility. EPA is testing such methods as Tenax filter analyzed by gas chromatography/mass spectroscopy (GC/MS), photoionization with differential GC columns, cryogenic trap followed by GC/MS, and MS/ MS. Preliminary results indicate that each of these methods has advantages and disadvantages. Since thestudy will take some timeto complete, multiple methods of analysis will probably be used to analyze each functional group of organic chemicals. Although EPA has not established monitoring method guidelines. the agency is developing a strategy to initiate toxin monitoring programs. The program is cxpected to begin in 1984 with monitoring networks in three cities. The most likely locations are Boston, Chicago, Houston, St. Louis, and the New York-New Jersey area. Each city would have one site located in an industrialized area. Two consecutive 12-h samples would probably be taken once every six days. I t is anticipated that a Tenax filter would be used and a dozen or more chemicals will be analyzed. The results of the program would give €PA an indication of the ambient levels of potentially toxic air pollutants in industrialized areas. By 1985. the program may be expanded to include 15 cities. Other monitoring programs are being designed to quantify the impacts of fugitive sources such as landfills and sewage treatment ponds.
1983 American Chemical Sock
Some state agency monitoring . grams have been enlarged to include sampling for metals and organics. New Jersev currentlv has the most extensive progiam. More than 50 substances are being monitored daily at four residential sites for six weeks in the summer and six weeks in the winter. Twenty-four-hour IP samples are analyzed for metals, arsenic, organic matter fraction, polycyclic aromatic hydrocarbons, bacterial mutagenicity, and sulfates. Volatile organic carbon samples are analyzed for pollutants regulated under New Jersey Administrative Code 27, Subchapter 17 and alkylating agents. Most state programs currently in operation analyze for fewer chemicals than the EPA network. Several states have invested in mobile units to supplement stationary networks and enable them to conduct special shortterm projects. Industry has been monitoring various polluthts in and around its own facilities, some for a number of years. These data, however, are not usually public information (unless they are submitted as part ofa permit application). Sincc no guidcline sampling methods have been defined for these pollutants, much of the available data is not comparable.
Future Monitoring of pollutants that are present in low concentrations (often close to detectable limits) will increase the need for stringent quality assurance and quality control. The sensitivity and application of certain measurement methods will continue to be a major concern among members of the regulated community. Next month's Regulatory Focus will discuss EPA', regulatory aeenda for toxic pollutants.
Richard M. Uowd. PhU. monoges Ihe Washington. D.('.,o//icrofEwironmpnml Research c4i Technology. Inc. YirM Sei. Technol.. Vol 17. No 11. 1983
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