10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Characterization and Quantification of Hexavalent Chromium and Other Air Toxic Metals in Communities Surrounding Metal Processing Facilities
EDWARD FORTNER, Paola Massoli, Tara Yacovitch, Scott Herndon, Andrey Khlystov, David Campbell, John Jayne, Aerodyne Research, Inc.
Abstract Number: 1286 Working Group: Aerosol Exposure
Abstract Hexavalent chromium is one of the seven hazardous air pollutants (HAPs) of primary importance to the U.S. EPA National Air Toxics Trends Stations (NATTS) program and it can be emitted into the atmosphere by facilities which conduct metal grinding, forging and plating operations if proper pollution control measures are not utilized. In March of 2018 the Aerodyne Mobile Laboratory (AML) conducted measurements of hexavalent chromium and other metals in the particle phase in an area in California focusing on the areas around businesses conducting these metal processing operations These facilities and neighborhoods have been studied previously with filter based measurements but this campaign was the first to conduct on-line fast time response (1 Hz) measurements of chromium in these areas that we are aware of.
The Aerodyne mobile lab contained a variety of fast time response instruments for the measurement of gas and particle phase species and features separate inlets for gas and particle phase species. Gas phase measurements included CO, CO2, NO2, NOx, O3 and selected VOC’s measured by proton transfer reaction mass spectrometry (PTR-MS). These gas phase species give useful insight regarding the chemical composition of the sampled air mass which can be related to sources. For the particulate chromium VI measurements key instrumentation included the Steam-Jet Aerosol Collector – Long Path Absorption Spectroscopy system (SJAC-LPAS) and the laser vaporization aerosol mass spectrometer (LV-AMS). The SJAC-LPAS conducted speciated measurements of Chromium VI and has a 15 second sampling time resolution but also has an 8 minute delay due to sample transfer from the point of collection to the optical cell. The LV-AMS detects chromium but is unable to determine the oxidation state., The unique attribute of the LV-AMS is that its fast time response (1 Hz) was used to locate chromium containing plumes which were then sampled with the SJAC-LPAS to speciate the chromium. Particle size information was also obtained with the LV-AMS and particle number concentration was determined with a condensation particle counter (CPC). Meteorological parameters of importance including wind direction are measured along with GPS coordinates to assist in plume mapping.