40 CFR § 98.43 - Calculating GHG emissions.

---
identifier: "/us/cfr/t40/s98.43"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 98.43 - Calculating GHG emissions."
title_number: 40
title_name: "Protection of Environment"
section_number: "98.43"
section_name: "Calculating GHG emissions."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "98"
part_name: "MANDATORY GREENHOUSE GAS REPORTING"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401-7671q."
regulatory_source: "74 FR 56374, Oct. 30, 2009, unless otherwise noted."
cfr_part: "98"
---


# 98.43 Calculating GHG emissions.

(a) Except as provided in paragraph (b) of this section, continue to monitor and report CO<sub>2</sub> mass emissions as required under § 75.13 or section 2.3 of appendix G to 40 CFR part 75, and § 75.64. Calculate CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O emissions as follows:

(1) Convert the cumulative annual CO<sub>2</sub> mass emissions reported in the fourth quarter electronic data report required under § 75.64 from units of short tons to metric tons. To convert tons to metric tons, divide by 1.1023.

(2) Calculate and report annual CH<sub>4</sub> and N<sub>2</sub>O mass emissions under this subpart by following the applicable method specified in § 98.33(c).

(b) Calculate and report biogenic CO<sub>2</sub> emissions under this subpart by following the applicable methods specified in § 98.33(e). The CO<sub>2</sub> emissions (excluding biogenic CO<sub>2</sub>) for units subject to this subpart that are reported under §§ 98.3(c)(4)(i) and (c)(4)(iii)(B) shall be calculated by subtracting the biogenic CO<sub>2</sub> mass emissions calculated according to § 98.33(e) from the cumulative annual CO<sub>2</sub> mass emissions from paragraph (a)(1) of this section. Separate calculation and reporting of biogenic CO<sub>2</sub> emissions is optional only for the 2010 reporting year pursuant to § 98.3(c)(12) and required every year thereafter.

[75 FR 79155, Dec. 17, 2010]