40 CFR § 53.2 - General requirements for a reference method determination.

---
identifier: "/us/cfr/t40/s53.2"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 53.2 - General requirements for a reference method determination."
title_number: 40
title_name: "Protection of Environment"
section_number: "53.2"
section_name: "General requirements for a reference method determination."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "53"
part_name: "AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "Sec. 301(a) of the Clean Air Act (42 U.S.C. sec. 1857g(a)), as amended by sec. 15(c)(2) of Pub. L. 91-604, 84 Stat. 1713, unless otherwise noted."
regulatory_source: "40 FR 7049, Feb. 18, 1975, unless otherwise noted."
cfr_part: "53"
---


# 53.2 General requirements for a reference method determination.

The following general requirements for a Federal reference method (FRM) determination are summarized in table A-1 of this subpart.

(a) *Manual methods*—(1) *Sulfur dioxide (SO*<sub>2</sub>) and Lead. For measuring SO<sub>2</sub> and lead, appendixes A-2 and G of part 50 of this chapter specify unique manual FRM for measuring those pollutants. Except as provided in § 53.16, other manual methods for lead will not be considered for a reference method determination under this part.

(2) *PM*<sub>10</sub>. A FRM for measuring PM <sub>10</sub> must be a manual method that meets all requirements specified in appendix J of part 50 of this chapter and must include a PM <sub>10</sub> sampler that has been shown in accordance with this part to meet all requirements specified in this subpart A and subpart D of this part.

(3) *PM*<sub>2.5</sub>. A FRM for measuring PM <sub>2.5</sub> must be a manual method that meets all requirements specified in appendix L of part 50 of this chapter and must include a PM <sub>2.5</sub> sampler that has been shown in accordance with this part to meet the applicable requirements specified in this subpart A and subpart E of this part. Further, FRM samplers must be manufactured in an ISO 9001-registered facility, as defined in § 53.1 and as set forth in § 53.51.

(4) *PM*<sub>10-2.5</sub>. A FRM for measuring PM <sub>10-2.5</sub> must be a manual method that meets all requirements specified in appendix O of part 50 of this chapter and must include PM <sub>10C</sub> and PM <sub>2.5</sub> samplers that have been shown in accordance with this part to meet the applicable requirements specified in this subpart A and subpart E of this part. Further, PM <sub>10-2.5</sub> FRM samplers must be manufactured in an ISO 9001-registered facility, as defined in § 53.1 and as set forth in § 53.51.

(b) *Automated methods.* An automated FRM for measuring SO<sub>2</sub>, CO, O<sub>3</sub>, or NO<sub>2</sub> must utilize the measurement principle and calibration procedure specified in the appropriate appendix to part 50 of this chapter (appendix A-1 only for SO<sub>2</sub> methods) and must have been shown in accordance with this part to meet the requirements specified in this subpart A and subpart B of this part.

[71 FR 61271, Oct. 17, 2006, as amended at 75 FR 35597, June 22, 2010]