---
kind: "section"
citation: "42 U.S.C. § 7671a"
title: "42"
title_heading: "The Public Health and Welfare"
number: "7671a"
heading: "Listing of class I and class II substances"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/42/7671a"
units:
  - "Chapter 85 — Air Pollution Prevention and Control"
  - "Subchapter VI — Stratospheric Ozone Protection"
---

# §7671a. Listing of class I and class II substances

- (a) **List of class I substances—** Within 60 days after November 15, 1990, the [Administrator](/usc/42/7602.md?p=a) shall publish an initial list of [class I substances](/usc/42/7671.md?p=3), which list shall contain the following substances:

  Group I

  chlorofluorocarbon-11 (CFC–11)

  chlorofluorocarbon-12 (CFC–12)

  chlorofluorocarbon-113 (CFC–113)

  chlorofluorocarbon-114 (CFC–114)

  chlorofluorocarbon-115 (CFC–115)

  Group II

  halon-1211

  halon-1301

  halon-2402

  Group III

  chlorofluorocarbon-13 (CFC–13)

  chlorofluorocarbon-111 (CFC–111)

  chlorofluorocarbon-112 (CFC–112)

  chlorofluorocarbon-211 (CFC–211)

  chlorofluorocarbon-212 (CFC–212)

  chlorofluorocarbon-213 (CFC–213)

  chlorofluorocarbon-214 (CFC–214)

  chlorofluorocarbon-215 (CFC–215)

  chlorofluorocarbon-216 (CFC–216)

  chlorofluorocarbon-217 (CFC–217)

  Group IV

  carbon tetrachloride

  Group V

  methyl chloroform

  The initial list under this subsection shall also include the isomers of the substances listed above, other than 1,1,2-trichloroethane (an isomer of methyl chloroform). Pursuant to [subsection (c)](#c), the [Administrator](/usc/42/7602.md?p=a) shall add to the list of [class I substances](/usc/42/7671.md?p=3) any other substance that the [Administrator](/usc/42/7602.md?p=a) finds causes or contributes significantly to harmful effects on the stratospheric ozone layer. The [Administrator](/usc/42/7602.md?p=a) shall, pursuant to [subsection (c)](#c), add to such list all substances that the [Administrator](/usc/42/7602.md?p=a) determines have an ozone depletion potential of 0.2 or greater.

- (b) **List of class II substances—** Simultaneously with publication of the initial list of [class I substances](/usc/42/7671.md?p=3), the [Administrator](/usc/42/7602.md?p=a) shall publish an initial list of [class II substances](/usc/42/7671.md?p=4), which shall contain the following substances:

  hydrochlorofluorocarbon-21 (HCFC–21)

  hydrochlorofluorocarbon-22 (HCFC–22)

  hydrochlorofluorocarbon-31 (HCFC–31)

  hydrochlorofluorocarbon-121 (HCFC–121)

  hydrochlorofluorocarbon-122 (HCFC–122)

  hydrochlorofluorocarbon-123 (HCFC–123)

  hydrochlorofluorocarbon-124 (HCFC–124)

  hydrochlorofluorocarbon-131 (HCFC–131)

  hydrochlorofluorocarbon-132 (HCFC–132)

  hydrochlorofluorocarbon-133 (HCFC–133)

  hydrochlorofluorocarbon-141 (HCFC–141)

  hydrochlorofluorocarbon-142 (HCFC–142)

  hydrochlorofluorocarbon-221 (HCFC–221)

  hydrochlorofluorocarbon-222 (HCFC–222)

  hydrochlorofluorocarbon-223 (HCFC–223)

  hydrochlorofluorocarbon-224 (HCFC–224)

  hydrochlorofluorocarbon-225 (HCFC–225)

  hydrochlorofluorocarbon-226 (HCFC–226)

  hydrochlorofluorocarbon-231 (HCFC–231)

  hydrochlorofluorocarbon-232 (HCFC–232)

  hydrochlorofluorocarbon-233 (HCFC–233)

  hydrochlorofluorocarbon-234 (HCFC–234)

  hydrochlorofluorocarbon-235 (HCFC–235)

  hydrochlorofluorocarbon-241 (HCFC–241)

  hydrochlorofluorocarbon-242 (HCFC–242)

  hydrochlorofluorocarbon-243 (HCFC–243)

  hydrochlorofluorocarbon-244 (HCFC–244)

  hydrochlorofluorocarbon-251 (HCFC–251)

  hydrochlorofluorocarbon-252 (HCFC–252)

  hydrochlorofluorocarbon-253 (HCFC–253)

  hydrochlorofluorocarbon-261 (HCFC–261)

  hydrochlorofluorocarbon-262 (HCFC–262)

  hydrochlorofluorocarbon-271 (HCFC–271)

  The initial list under this subsection shall also include the isomers of the substances listed above. Pursuant to [subsection (c)](#c), the [Administrator](/usc/42/7602.md?p=a) shall add to the list of [class II substances](/usc/42/7671.md?p=4) any other substance that the [Administrator](/usc/42/7602.md?p=a) finds is known or may reasonably be anticipated to cause or contribute to harmful effects on the stratospheric ozone layer.

- (c) **Additions to the lists—**
  - (1) The [Administrator](/usc/42/7602.md?p=a) may add, by rule, in accordance with the criteria set forth in subsection [(a)](#a) or [(b)](#b), as the case may be, any substance to the list of class I or [class II substances](/usc/42/7671.md?p=4) under subsection [(a)](#a) or [(b)](#b). For purposes of exchanges under [section 7661f](/usc/42/7661f.md)[^1] of this title, whenever a substance is added to the list of [class I substances](/usc/42/7671.md?p=3) the [Administrator](/usc/42/7602.md?p=a) shall, to the extent consistent with the [Montreal Protocol](/usc/42/7671.md?p=9), assign such substance to existing Group I, II, III, IV, or V or place such substance in a new Group.
  - (2) Periodically, but not less frequently than every 3 years after November 15, 1990, the [Administrator](/usc/42/7602.md?p=a) shall list, by rule, as additional class I or [class II substances](/usc/42/7671.md?p=4) those substances which the [Administrator](/usc/42/7602.md?p=a) finds meet the criteria of subsection [(a)](#a) or [(b)](#b), as the case may be.
  - (3) At any time, any [person](/usc/42/7602.md?p=e) may petition the [Administrator](/usc/42/7602.md?p=a) to add a substance to the list of class I or [class II substances](/usc/42/7671.md?p=4). Pursuant to the criteria set forth in subsection [(a)](#a) or [(b)](#b) as the case may be, within 180 days after receiving such a petition, the [Administrator](/usc/42/7602.md?p=a) shall either propose to add the substance to such list or publish an explanation of the petition denial. In any case where the [Administrator](/usc/42/7602.md?p=a) proposes to add a substance to such list, the [Administrator](/usc/42/7602.md?p=a) shall add, by rule, (or make a final determination not to add) such substance to such list within 1 year after receiving such petition. Any petition under this paragraph shall include a showing by the petitioner that there are data on the substance adequate to support the petition. If the [Administrator](/usc/42/7602.md?p=a) determines that information on the substance is not sufficient to make a determination under this paragraph, the [Administrator](/usc/42/7602.md?p=a) shall use any authority available to the [Administrator](/usc/42/7602.md?p=a), under any law administered by the [Administrator](/usc/42/7602.md?p=a), to acquire such information.
  - (4) Only a [class II substance](/usc/42/7671.md?p=4) which is added to the list of [class I substances](/usc/42/7671.md?p=3) may be removed from the list of [class II substances](/usc/42/7671.md?p=4). No substance referred to in [subsection (a)](#a), including methyl chloroform, may be removed from the list of [class I substances](/usc/42/7671.md?p=3).
- (d) **New listed substances—** In the case of any substance added to the list of class I or [class II substances](/usc/42/7671.md?p=4) after publication of the initial list of such substances under this section, the [Administrator](/usc/42/7602.md?p=a) may extend any schedule or compliance deadline contained in section [7671c](/usc/42/7671c.md) or [7671d](/usc/42/7671d.md) of this title to a later date than specified in such sections if such schedule or deadline is unattainable, considering when such substance is added to the list. No extension under this subsection may extend the date for termination of [production](/usc/42/7671.md?p=11) of any [class I substance](/usc/42/7671.md?p=3) to a date more than 7 years after January 1 of the year after the year in which the substance is added to the list of [class I substances](/usc/42/7671.md?p=3). No extension under this subsection may extend the date for termination of [production](/usc/42/7671.md?p=11) of any [class II substance](/usc/42/7671.md?p=4) to a date more than 10 years after January 1 of the year after the year in which the substance is added to the list of [class II substances](/usc/42/7671.md?p=4).
- (e) **Ozone-depletion and global warming potential—** Simultaneously with publication of the lists under this section and simultaneously with any addition to either of such lists, the [Administrator](/usc/42/7602.md?p=a) shall assign to each listed substance a numerical value representing the substance’s [ozone-depletion potential](/usc/42/7671.md?p=10). In addition, the [Administrator](/usc/42/7602.md?p=a) shall publish the chlorine and bromine loading potential and the atmospheric lifetime of each listed substance. One year after November 15, 1990 (one year after the addition of a substance to either of such lists in the case of a substance added after the publication of the initial lists of such substances), and after notice and opportunity for public comment, the [Administrator](/usc/42/7602.md?p=a) shall publish the global warming potential of each listed substance. The preceding sentence shall not be construed to be the basis of any additional regulation under this chapter. In the case of the substances referred to in table 1, the [ozone-depletion potential](/usc/42/7671.md?p=10) shall be as specified in table 1, unless the [Administrator](/usc/42/7602.md?p=a) adjusts the substance’s [ozone-depletion potential](/usc/42/7671.md?p=10) based on criteria referred to in [section 7671(10) of this title](/usc/42/7671.md?p=10):

  | Table 1 |  |
  | --- | --- |
  | Substance | Ozone- depletion potential |
  | chlorofluorocarbon-11 (CFC–11) | 1.0 |
  | chlorofluorocarbon-12 (CFC–12) | 1.0 |
  | chlorofluorocarbon-13 (CFC–13) | 1.0 |
  | chlorofluorocarbon-111 (CFC–111) | 1.0 |
  | chlorofluorocarbon-112 (CFC–112) | 1.0 |
  | chlorofluorocarbon-113 (CFC–113) | 0.8 |
  | chlorofluorocarbon-114 (CFC–114) | 1.0 |
  | chlorofluorocarbon-115 (CFC–115) | 0.6 |
  | chlorofluorocarbon-211 (CFC–211) | 1.0 |
  | chlorofluorocarbon-212 (CFC–212) | 1.0 |
  | chlorofluorocarbon-213 (CFC–213) | 1.0 |
  | chlorofluorocarbon-214 (CFC–214) | 1.0 |
  | chlorofluorocarbon-215 (CFC–215) | 1.0 |
  | chlorofluorocarbon-216 (CFC–216) | 1.0 |
  | chlorofluorocarbon-217 (CFC–217) | 1.0 |
  | halon-1211 | 3.0 |
  | halon-1301 | 10.0 |
  | halon-2402 | 6.0 |
  | carbon tetrachloride | 1.1 |
  | methyl chloroform | 0.1 |
  | hydrochlorofluorocarbon-22 (HCFC–22) | 0.05 |
  | hydrochlorofluorocarbon-123 (HCFC–123) | 0.02 |
  | hydrochlorofluorocarbon-124 (HCFC–124) | 0.02 |
  | hydrochlorofluorocarbon-141(b) (HCFC–141(b)) | 0.1 |
  | hydrochlorofluorocarbon-142(b) (HCFC–142(b)) | 0.06 |

  Where the [ozone-depletion potential](/usc/42/7671.md?p=10) of a substance is specified in the [Montreal Protocol](/usc/42/7671.md?p=9), the [ozone-depletion potential](/usc/42/7671.md?p=10) specified for that substance under this section shall be consistent with the [Montreal Protocol](/usc/42/7671.md?p=9).


## Footnotes

[^1]: So in original. Probably should be section “7671f”.

## Source credit

(July 14, 1955, ch. 360, title VI, § 602, as added Pub. L. 101–549, title VI, § 602(a), Nov. 15, 1990, 104 Stat. 2650.)