| Title: | A field comparison of volatile organic compound measurements using passive organic vapor monitors and stainless steel canisters |
| Author(s): | Pratt GC; Bock D; Stock TH; Morandi M; Adgate JL; Ramachandran G; Mongin SJ; Sexton K; |
| Address: | "Environmental Outcomes Division, Minnesota Pollution Control Agency, 520 Lafayette Road, St. Paul, Minnesota 55155, USA. gregory.pratt@pca.state.mn.us" |
| ISSN/ISBN: | 0013-936X (Print) 0013-936X (Linking) |
| Abstract: | "Concurrent field measurements of 10 volatile organic compounds (VOCs) were made using passive diffusion-based organic vapor monitors (OVMs) and the U.S. Federal Reference Method, which comprises active monitoring with stainless steel canisters (CANs). Measurements were obtained throughout a range of weather conditions, repeatedly over the course of three seasons, and at three different locations in the Minneapolis/St. Paul metropolitan area. Ambient concentrations of most VOCs as measured by both methods were low compared to those of other large metropolitan areas. For some VOCs a considerable fraction of measurements was below the detection limit of one or both methods. The observed differences between the two methods were similar across measurement sites, seasons, and meteorological variables. A Bayesian analysis with uniform priors on the differences was applied, with accommodation of sometimes heavy censoring (nondetection) in either device. The resulting estimates of bias and standard deviation of the OVM relative to the CAN were computed by tertile of the canister-measured concentration. In general, OVM and CAN measurements were in the best agreement for benzene and other aromatic compounds with hydrocarbon additions (ethylbenzene, toluene, and xylenes). The two methods were not in such good agreement for styrene and halogenated compounds (carbon tetrachloride, p-dichlorobenzene, methylene chloride, and trichloroethylene). OVMs slightly overestimated benzene concentrations and carbon tetrachloride at low concentrations, but in all other cases where significant differences were found, OVMs underestimated relative to canisters. Our study indicates that the two methods are in agreement for some compounds, but not all. We provide data and interpretation on the relative performance of the two VOC measurement methods, which facilitates intercomparisons among studies" |
| Keywords: | Air Pollutants/*analysis Diffusion Environmental Monitoring/*instrumentation Meteorological Concepts Organic Chemicals/analysis Seasons Volatilization; |
| Notes: | "MedlinePratt, Gregory C Bock, Don Stock, Thomas H Morandi, Maria Adgate, John L Ramachandran, Gurumurthy Mongin, Steven J Sexton, Ken eng Comparative Study Evaluation Study Research Support, U.S. Gov't, Non-P.H.S. 2005/06/02 Environ Sci Technol. 2005 May 1; 39(9):3261-8. doi: 10.1021/es0497328" |
