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EVALUATION OF THE LOADING CHARACTERISTICS OF THE EPA WINS PM 2.5 SEPARATOR
Citation:
Vanderpool, R. W., T. Peters, S. Natarajan, D B. Gemmill, AND R W. Wiener. EVALUATION OF THE LOADING CHARACTERISTICS OF THE EPA WINS PM 2.5 SEPARATOR. AEROSOL SCIENCE AND TECHNOLOGY 34(5):444-456, (2001).
Impact/Purpose:
The core aerosol research for FY01 includes evaluation of newly developed and developing methods for the chemical analysis and sampling of PM in ambient air, especially state-of-the-art continuous and non-invasive aerosol measurement methods, and the study of the aerosol sampling processes to better assess the true aerosol concentration and size distributions observed in the ambient environment. An additional emphasis is placed on integrated sampling for stable and semi-volatile organic aerosol species. This latter area addresses the state-of-the-art in this measurement area. This program supports Title I of the Clean Air Act in its mandate for performing research to support the NAAQS, GPRA goal 1.1.5, and ORD's main research objective on PM.
Much of this work directly supports OAQPS and may be applied within the Supersites Program managed jointly by OAQPS and ORD. This research also will support many of ORD's long-term research goals by providing more reliable information (decrease uncertainty) on ambient aerosols that can be utilized for characterizing risk.
Finally, an APM, has been established to develop measurement methods for causal factors, due in 2004. Currently, there are a number of causal factor hypotheses, but none have sufficient evidence to support developing one measurement/analytical method over another. The PM methods team will support and work with Joellen Lewtas on methods for the collection and analysis of semi-volatile and aerosol phase organic species to help address this APM. The PM methods team will continue to work within the Supersites program and with OAQPS and their new partners in ORIA to further evaluate continuous species specific methods and aerosol physical property measurement methods.
Description:
The loading characteristics of the USEPA WINS (Well Impactor Ninety Six) PM2.5 separator was an important design consideration during the separator's development. In recognition that all inertial separators eventually overload, the loading surface of the WINS was designed to be easily accessible, replaceable, and cleanable. Prior to promulgation of the method, the loading capacity of the WINS separator was evaluated by measuring its performance after repeated loading with laboratory-generated, high concentration, coarse-mode aerosol. For this purpose, a low flow rate loading wind tunnel was designed and constructed to artificially create coarse mode aerosols composed of Arizona Test Dust. This controlled test atmosphere was sampled by the PM2.5 reference method sampling train, as specified in 40 CFR Part 50, Appendix L, at total aerosol mass concentrations averaging 332 ug/m3 for three 24-hour periods. The particle size fractionation characteristics of the WINS was evaluated in the laboratory after each 24-hour sampling event. These performance curves were integrated with three idealized ambient distributions to yield estimates of bias in measured mass concentration with respect to a clean WINS. Test results served as the basis for establishing the required cleaning frequency of the sampler during field use. Following the method's promulgation, characterization of the WINS performance under conditions of actual field use at five U.S. cities showed that a maximum mass concentration bias of -2.1% was estimated for 13 wells after the 5-day sampling period. Overall study results supported the current regulation (USEPA, 1998) that WINS wells be replaced after every 5 days of 24-hour operation.
This work was conducted by Research Triangle Institute with support provided by the U.S. Environmental Protection Agency through contract no. 68-D5-0040. It has been reviewed in accordance with the Agency's peer and administrative review policies and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation by RTI or the Agency.