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Ambient Air Monitoring Reference and Equivalent Methods; Designation of One New Reference Method

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Office of Research and Development; Environmental Protection Agency.


Notice of the designation of a new reference method for monitoring ambient air quality.


Notice is hereby given that the Environmental Protection Agency (EPA) has designated one new reference method for measuring concentrations of nitrogen dioxide (NO2) in ambient air.

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Robert Vanderpool, Exposure Methods and Measurement Division (MD-D205-03), National Exposure Research Laboratory, U.S. EPA, Research Triangle Park, North Carolina 27711. Phone: 919-541-7877. Email:

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In accordance with regulations at 40 CFR part 53, the EPA evaluates various methods for monitoring the concentrations of those ambient air pollutants for which EPA has established National Ambient Air Quality Standards (NAAQS) as set forth in 40 CFR part 50. Monitoring methods that are determined to meet specific requirements for adequacy are designated by the EPA as either reference or equivalent methods (as applicable), thereby permitting their use under 40 CFR part 58 by States and other agencies for determining compliance with the NAAQS. A list of all reference or equivalent methods that have been previously designated by EPA may be found at​ttn/​amtic/​criteria.html.

The EPA hereby announces the designation of one new reference method for measuring concentrations of NO2 in ambient air. This designation is made under the provisions of 40 CFR part 53, as amended on October 26, 2015(80 FR 65291-65468).

The new reference method for NO2 is an automated method (analyzer) utilizing the measurement principle based on gas phase chemiluminescence. This newly designated reference method is identified as follows:

RFNA-0418-250, “Sabio Model 6040 Ambient NO/NO2/NOX Analyzer”, operated in the measurement range of 0-0.5 PPM, an any ambient temperature in the range of 5-40 °C, within a line voltage range determined by the selected optional pump [115 VAC external pump: 105-125 VAC (60 Hz); 230 VAC external pump: 210-250 VAC (50-60 Hz); 24 VDC internal pump: 90-260 VAC (50-60 Hz)], at any sample flow rate in the range of 0.50-0.75 L/min, in accordance with the “Sabio Model 6040 Ambient NO/NO2/NOX Analyzer Instruction Manual”, with or without optional zero/span ports for external calibration, and with or without an optional inlet filter.

This application for a reference method determination for this NO2 method was received by the Office of Research and Development on March 28, 2018. This analyzer is commercially available from the applicant, Sutron Corporation, 21 Cypress Blvd., Suite 1130, Round Rock, TX 78665.

A representative test analyzer was tested in accordance with the applicable test procedures specified in 40 CFR part 53, as amended on October 26, 2015. After reviewing the results of those tests and other information submitted by the applicant, EPA has determined, in accordance with part 53, that this method should be designated as a reference method.

As a designated reference method, this method is acceptable for use by states and other air monitoring agencies under the requirements of 40 CFR part 58, Ambient Air Quality Surveillance. For such purposes, this method must be used in strict accordance with the operation or instruction manual associated with the method and subject to any specifications and limitations (e.g., configuration or operational settings) specified in the designated method description (see the identification of the method above).

Use of the method also should be in general accordance with the guidance and recommendations of applicable sections of the “Quality Assurance Handbook for Air Pollution Measurement Systems, Volume I,” EPA/600/R-94/038a and “Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II, Ambient Air Quality Monitoring Program,” EPA-454/B-13-003, (both available at​ttn/​amtic/​qalist.html). Provisions concerning modification of such methods by users are specified under Section 2.8 (Modifications of Methods by Users) of Appendix C to 40 CFR part 58.

Consistent or repeated noncompliance with any of these conditions should be reported to: Director, Exposure Methods and Measurement Division (MD-E205-01), National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711.

Designation of this reference method is intended to assist the States in establishing and operating their air quality surveillance systems under 40 CFR part 58. Questions concerning the commercial availability or technical aspects of the method should be directed to the applicant.

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Dated: May 21, 2018.

Timothy Watkins,

Director, National Exposure Research Laboratory.

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[FR Doc. 2018-11832 Filed 5-31-18; 8:45 am]