Pet Safety / Compounds / R-744 (Carbon dioxide / CO2 refrigerant)

Is R-744 (Carbon dioxide / CO2 refrigerant) safe for dogs and cats?

Moderate risk for pets

Nose-level closer to floor where CO2 pools. Several pet fatalities from CO2 leaks in commercial spaces.

What is r-744 (carbon dioxide / co2 refrigerant)?

Also known as: carbon dioxide, carbonic anhydride, 124-38-9, carbonic acid gas.

CAS number
124-38-9
Molecular formula
CO2
Molecular weight
44.01 g/mol
SMILES
C(=O)=O
PubChem CID
280

Risk for dogs

Moderate risk

Nose-level closer to floor where CO2 pools. Several pet fatalities from CO2 leaks in commercial spaces.

Risk for cats

Moderate risk

Same floor-level accumulation concern as dogs.

Regulatory consensus

6 regulatory and scientific bodies have classified R-744 (Carbon dioxide / CO2 refrigerant). The classifications differ — that's the data.

AgencyYearClassificationNotes
ASHRAE 34—A1 — lower toxicity, non-flammable
OSHA—PEL 5000 ppm TWA, no STEL. NIOSH REL 5000 ppm TWA, 30,000 ppm STEL
EU F GAS—Natural refrigerant — exempt from F-gas regulation. Actively promoted as HFC replacement
EPA SNAP—Listed as acceptable substitute in many end uses with use conditions
EN 378—European standard for refrigerating systems and heat pumps — specific provisions for CO2 high-pressure systems
KIGALI AMENDMENT—Not regulated (natural substance)

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where pets encounter r-744 (carbon dioxide / co2 refrigerant)

  • Supermarket Refrigeration — Transcritical CO2 systems — ~50% of new European supermarkets, growing in US
  • Heat Pumps — EcoCute heat pump water heaters (Japan — >7 million installed)
  • Vending Machines — Coca-Cola, Pepsi using CO2 vending machines globally
  • Vehicle Ac — Under development/testing as R-1234yf alternative (Daimler tested extensively)
  • Industrial — Ice rinks, cold storage, food processing blast freezers
  • Cascade Systems — Low-temperature stage in cascade with HFC or ammonia high stage

Safer alternatives

Lower-risk approaches that achieve a similar outcome to R-744 (Carbon dioxide / CO2 refrigerant):

  • R-290 (Propane)
    Trade-offs: Removes 95-99% of dissolved contaminants including metals, PFAS, nitrates; wastes 2-4 gallons per gallon produced (improving with newer systems); removes beneficial minerals; $0.05-0.25/gallon; requires pre-treatment for longevity.
    Relative cost: 1.2-2×
  • R-717 (Ammonia)
    Trade-offs: Alternative approach; specific tradeoffs depend on application context, scale, and regulatory requirements. Full hazard assessment of alternative recommended before adoption to avoid regrettable substitution.
    Relative cost: 1.2-2×

Frequently asked questions

Is r-744 (carbon dioxide / co2 refrigerant) safe for pets?

Nose-level closer to floor where CO2 pools. Several pet fatalities from CO2 leaks in commercial spaces.

What products contain r-744 (carbon dioxide / co2 refrigerant)?

R-744 (Carbon dioxide / CO2 refrigerant) appears in: Transcritical CO2 systems — ~50% of new European supermarkets, growing in US (Supermarket Refrigeration); EcoCute heat pump water heaters (Japan — >7 million installed) (Heat Pumps); Coca-Cola, Pepsi using CO2 vending machines globally (Vending Machines).

Why do regulators disagree about r-744 (carbon dioxide / co2 refrigerant)?

R-744 (Carbon dioxide / CO2 refrigerant) has been classified by 6 agencies including ASHRAE 34, OSHA, EU F GAS, EPA SNAP, EN 378, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.

See R-744 (Carbon dioxide / CO2 refrigerant) in the pets app

Look up products containing r-744 (carbon dioxide / co2 refrigerant), compare to alternatives, and explore the full data record.

Open in pets View raw API data

Sources (1)
  1. — expert_curation

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →