• EPA SNAP Program: Governs HFOs under the Significant New Alternatives Policy (SNAP), which approves substitutes for ozone-depleting substances (ODS) and high-GWP HFCs.

• AIM Act (2020): Mandates an 85% phasedown of HFC production/consumption by 2036, driving HFO adoption.

• Clean Air Act (Section 612): Requires EPA to evaluate environmental and health impacts of alternatives like HFOs.

a. Approved HFOs & Uses (EPA SNAP Listings)

• HFO-1234yf: Approved for motor vehicle AC (MY 2021+), supermarket refrigeration, and chillers.

• HFO-1234ze: Approved for foam blowing, aerosols, and stationary AC.

• HFO-1336mzz: Approved for industrial heat pumps and fire suppression.

• Restrictions: Some HFOs (e.g., HFO-1234yf) require flammability risk mitigation (ASHRAE Standard 34/UL 60335-2-40).

b. GWP Limits

• Sector-Specific Caps:

  • Retail Food Refrigeration: GWP ≤ 150 (2025 onward).

  • Residential AC: GWP ≤ 750 (2025 onward).

• AIM Act HFC Allowances: HFOs are exempt from HFC quotas if GWP < 53 (e.g., HFO-1234yf: GWP = 4).

c. Safety & Labeling

• ASHRAE Classification:

  • A2L (low toxicity, mildly flammable) for most HFOs.

  • Requires leak detection systems and ventilation in confined spaces.

• DOT/PHMSA Transport Rules:

  • HFOs classified as hazardous materials (UN numbers, e.g., UN3163 for HFO-1234yf).

  • Mandatory cylinder testing (DOT 4BA/4BW) and flammability labels.

d. State-Level Rules

• California (CARB): Stricter GWP limits (e.g., GWP ≤ 150 for new stationary AC by 2025).

• Washington, New York: Adopt CARB-like standards under Climate Superfund initiatives.

• Verify SNAP Approval: Confirm HFO is listed for intended use (EPA SNAP Database).

• Submit EPA Notifications: For imports/exports under TSCA (Toxic Substances Control Act).

• Track HFC Allowances: Only applies if blending HFOs with regulated HFCs.

• Label & Train:

  • Mark containers with GWP, safety warnings, and UN codes.

  • Train technicians per EPA Section 608 (refrigerant handling).

• Report Emissions: For HFOs with GWP ≥ 1, submit to EPA GHGRP (Greenhouse Gas Reporting Program).

• 2023 SNAP Rule 26: Expanded HFO approvals for data center cooling and commercial ice machines.

• 2024 AIM Act Adjustments: Reduced HFC production quotas (40% below baseline), accelerating HFO demand.

• CARB Scoping Plan: Targets 40% HFC emission cuts by 2030, favoring HFO retrofits.

• Fines: Up to $99,681 per violation/day (Clean Air Act).

• Shipment Holds: Customs may block imports lacking SNAP/TSCA documentation.

• Revoked Licenses: Repeat offenders risk losing refrigerant handling certifications.