EPA Supply Chain GHG Emission Factors

The EPA Supply Chain Greenhouse Gas Emission Factors map each US industry or commodity (by six-digit NAICS code) to the greenhouse-gas emissions generated per dollar of its output, expressed as kilograms of carbon-dioxide equivalent per US dollar. They let you attach an emissions intensity to spending or revenue by industry without firm-level emissions data. The factors are built by the Environmental Protection Agency from the USEEIO environmentally-extended input-output model and are free and public. Used in, for example, Allcott, Montanari, Ozaltun & Tan, in the corporate-social-impact analysis.

• Cost: free, public.
• API key: none required.
• Coverage: roughly 1,000 commodities at six-digit NAICS; one factor set per release (v1.3 uses 2017 NAICS, 2022 USD, AR5 100-year GWP).
• Home: https://www.epa.gov/climateleadership/supply-chain-greenhouse-gas-emission-factors

Access

The factor table is a single CSV, no authentication. The CO2e file gives all gases combined; a by-GHG file breaks them out by gas:

# Supply Chain GHG factors v1.3, all GHGs combined (CO2e), 2022 USD, no key
curl -sL -o SupplyChainGHGEmissionFactors_v1.3.0_NAICS_CO2e_USD2022.csv \
  "https://pasteur.epa.gov/uploads/10.23719/1531143/SupplyChainGHGEmissionFactors_v1.3.0_NAICS_CO2e_USD2022.csv"
# By individual greenhouse gas:
curl -sL -o SupplyChainGHGEmissionFactors_v1.3.0_NAICS_byGHG_USD2022.csv \
  "https://pasteur.epa.gov/uploads/10.23719/1531143/SupplyChainGHGEmissionFactors_v1.3.0_NAICS_byGHG_USD2022.csv"

The CO2e file has one row per six-digit NAICS code with columns: 2017 NAICS Code, 2017 NAICS Title, GHG, Unit, Supply Chain Emission Factors without Margins, Margins of Supply Chain Emission Factors, Supply Chain Emission Factors with Margins, and Reference USEEIO Code. The unit is kg CO2e per 2022 USD at purchaser price.

Load in Python

import pandas as pd

df = pd.read_csv(
    "SupplyChainGHGEmissionFactors_v1.3.0_NAICS_CO2e_USD2022.csv",
    dtype={"2017 NAICS Code": str},
)
# Attach intensity to spend: emissions_kgCO2e = spend_usd * factor_with_margins
factor = df.set_index("2017 NAICS Code")["Supply Chain Emission Factors with Margins"]

Gotchas (the ones that bite pipelines)

• With-margins versus without-margins are different numbers. “Without margins” is the production emissions per producer-price dollar; “with margins” adds the transport, wholesale, and retail margins so the factor applies to a purchaser-price dollar (what a buyer actually pays). Multiply spend at purchaser prices by the with-margins factor; mixing the two double-counts or undercounts.
• The factor’s USD year is fixed; deflate your spend to match. v1.3 factors are per 2022 dollar. Spending in another year’s dollars must be deflated to the factor’s USD year before multiplying, or the intensity is off by inflation.
• NAICS vintage matters for the join. v1.3 keys on 2017 NAICS codes. Firm or transaction data coded to a different NAICS vintage (2012, 2022) needs a concordance first; a code can shift industries across vintages.
• Versions change methodology, not just numbers. v1.2 (2021 USD) and v1.3 (2022 GHG data, 2022 USD) differ in the emissions-data year, USD year, and minor method. Pin one version across a project and cite it.
• A few sectors are excluded. Electricity, government, and households are not given factors at the six-digit level. Spend mapped to those NAICS has no factor; handle it explicitly rather than letting it drop to zero.
• It is a spend-based average, not a firm measurement. The factor is the industry-average emissions per dollar from an input-output model, not any one firm’s footprint. Two firms in the same NAICS get the same intensity per dollar regardless of their actual technology.

Factor columns

Column	Meaning
Supply Chain Emission Factors without Margins	kg CO2e per producer-price USD
Margins of Supply Chain Emission Factors	the transport/wholesale/retail margin component
Supply Chain Emission Factors with Margins	kg CO2e per purchaser-price USD (without + margins)
Reference USEEIO Code	the USEEIO model commodity the factor maps to

Citation

Cite the EPA, the dataset and version, the NAICS and USD year, the URL, and the access date, for example: U.S. Environmental Protection Agency, Supply Chain Greenhouse Gas Emission Factors v1.3 (2017 NAICS, 2022 USD), retrieved from https://www.epa.gov/climateleadership/supply-chain-greenhouse-gas-emission-factors, accessed YYYY-MM-DD. Record the version, the with/without-margins choice, and the USD year so the calculation is reproducible.