2023-03578: Reference Measurement Principle and Calibration Procedure for the Measurement of Ozone in the Atmosphere (Chemiluminescence Method)
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The Environmental Protection Agency (EPA) is proposing to update the current ozone absorption cross-section to the recommended consensus-based cross-section value of 1.1329x10<SUP>-</SUP>\17\ cm\2\ molecule<SUP>-</SUP>\1\ or 304.39 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\, with an uncertainty of 0.94 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\. The new value is 1.2% lower than the current value of 308 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\, and reduces the uncertainty in the value to 0.31%. The adoption of this updated ozone absorption cross-section could result in increases in measured ozone concentrations but given the existing sources of potential variability in monitoring data, it is unlikely that there would be any consistent measurable and predictable effect on reported data. The EPA is also proposing to update the dates of publication for two references, add a new reference for the updated cross-section value, and move the figures inadvertently placed in Section 6.0 References to a new Section 7.0 Figures.
The agency’s own summary, as published.
What this changes
Amends 1 part of the Code of Federal Regulations — the standing rules this notice rewrites.
Rulemaking docket
We haven’t pulled this rulemaking’s full docket yet. View docket EPA-HQ-OAR-2022-0007 on Regulations.gov →
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