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Performance of the Proposed New Federal Reference Methods for Measuring Ozone Concentrations in Ambient Air
Citation:
Long, R., E. Hall, M. Beaver, R. Duvall, S. Kaushik, K. Kronmiller, M. Wheeler, S. Garvey, Z. Drake, AND F. McElroy. Performance of the Proposed New Federal Reference Methods for Measuring Ozone Concentrations in Ambient Air. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-14/432 (NTIS PB2015-101240), 2014.
Impact/Purpose:
The National Exposure Research Laboratory’s (NERL’s) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA’s mission to protect human health and the environment. HEASD’s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA’s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air, described in EPA regulations at 40 CFR Part 50, Appendix D, is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O3) that may be present in air samples. This methodology is technically sound and has well served its role in O3 monitoring and as an FRM for many years since its establishment in 1971. However, the method now no longer meets the full needs of an FRM because no manufacturer of O3 monitoring instruments currently offers an FRM analyzer for sale. Existing FRM analyzers are largely obsolete and poorly supported (if supported at all) by their manufacturers, and consequently all current O3 monitoring is carried out with other types of monitors (equivalent methods). A new FRM for O3 is needed to meet the needs that the existing FRM can no longer fulfill. A rather similar measurement method, based on the dry, gas-phase, chemiluminescence reaction between nitric oxide (NO) and any O3 present in ambient samples has been subjected to extensive laboratory and field testing (along with an FRM and other FEM methods) to determine its performance and other attributes relative to those of the existing FRM. This report describes the nature and results of this testing and documents the conclusion that this alternative, NO-chemiluminescence (NO-CL) method has performance as good as − or better than − the existing FRM. Further, at least two NO-chemiluminescence O3 monitoring analyzers are commercially available (from one manufacturer) and have been designated by the EPA as Federal equivalent methods (FEMs) for use in ozone monitoring networks. Therefore, this alternative method is shown to be well suited as a supplemental FRM for O3 to serve in the FRM role as a practical reference standard for candidate FEMs and for quality assurance of ozone monitoring data.