EPA Envirofacts API Reference

Base URL

https://data.epa.gov/efservice

Note: The legacy URL https://enviro.epa.gov/enviro/efservice may redirect. Use the current base URL above.

Authentication

None required. Fully public, no API key needed.

Rate Limits

• No documented per-user rate limit.
• Large result sets may time out. Use row limits and pagination.

URL Pattern

Envirofacts uses a RESTful URL-based query pattern:

https://data.epa.gov/efservice/{table}/{column}/{operator}/{value}/.../rows/{start}:{end}/{format}

• {table}: Database table name (e.g. TRI_FACILITY, AQS_SITES).
• {column}/{operator}/{value}: Filter conditions, chained in the URL path.
• Operators: = (implicit, just use /{column}/{value}), >, <, !=, BEGINNING (starts with), CONTAINING.
• rows/{start}:{end}: Row range for pagination (0-based).
• {format}: JSON, XML, CSV, EXCEL. Appended as the last path segment.

Multiple filters are chained sequentially in the URL path.

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Key Databases and Tables

1. Toxics Release Inventory (TRI)

Tracks releases of toxic chemicals from industrial facilities.

Key Tables:

Example -- TRI facilities in North Carolina:

https://data.epa.gov/efservice/TRI_FACILITY/STATE_ABBR/NC/rows/0:9/JSON

Response:

[
  {
    "TRI_FACILITY_ID": "27601MPLNT501WE",
    "FACILITY_NAME": "EXAMPLE MANUFACTURING PLANT",
    "STREET_ADDRESS": "501 WEST MAIN ST",
    "CITY_NAME": "RALEIGH",
    "COUNTY_NAME": "WAKE",
    "STATE_ABBR": "NC",
    "ZIP_CODE": "27601",
    "LATITUDE": 35.7796,
    "LONGITUDE": -78.6382,
    "FEDERAL_FACILITY_FLAG": "NO",
    "INDUSTRY_SECTOR_CODE": "325",
    "PRIMARY_SIC_CODE": "2819",
    "PRIMARY_NAICS_CODE": "325180"
  }
]

Example -- TRI releases of a specific chemical in a state (2022):

https://data.epa.gov/efservice/TRI_RELEASE_QTY/STATE_ABBR/TX/REPORTING_YEAR/2022/CHEM_NAME/CONTAINING/BENZENE/rows/0:24/JSON

2. Air Quality System (AQS)

Air quality monitoring data from the national monitoring network.

Key Tables:

Example -- AQS monitoring sites in California:

https://data.epa.gov/efservice/AQS_SITES/STATE_CODE/06/rows/0:9/JSON

Example -- annual ozone summary for a county:

https://data.epa.gov/efservice/AQS_ANNUAL_SUMMARY/STATE_CODE/06/COUNTY_CODE/037/PARAMETER_CODE/44201/rows/0:9/JSON

Common AQS Parameter Codes:

3. Facility Registry Service (FRS)

Central registry of EPA-regulated facilities.

Key Tables:

Example -- EPA-regulated facilities by zip code:

https://data.epa.gov/efservice/FRS_FACILITY_SITE/POSTAL_CODE/90210/rows/0:9/JSON

4. Safe Drinking Water (SDWIS)

Public drinking water system data.

Key Tables:

Example -- drinking water violations in a state:

https://data.epa.gov/efservice/VIOLATION/PWSID/BEGINNING/OH/rows/0:19/JSON

5. Greenhouse Gas Reporting (GHG)

Facility-level greenhouse gas emissions data.

Key Tables:

Example -- GHG facilities in a state:

https://data.epa.gov/efservice/PUB_DIM_FACILITY/STATE/TX/rows/0:9/JSON

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Query Patterns

Filtering with operators

# Exact match (implicit =)
/TABLE/COLUMN/VALUE/JSON

# Greater than
/TABLE/COLUMN/>/VALUE/JSON

# Less than
/TABLE/COLUMN/</VALUE/JSON

# Not equal
/TABLE/COLUMN/!=/VALUE/JSON

# Starts with
/TABLE/COLUMN/BEGINNING/VALUE/JSON

# Contains
/TABLE/COLUMN/CONTAINING/VALUE/JSON

Combining filters

Chain multiple column/value pairs:

/TABLE/COLUMN1/VALUE1/COLUMN2/VALUE2/JSON

Pagination

Use rows/{start}:{end} (0-based, inclusive):

/TABLE/rows/0:99/JSON       # First 100 rows
/TABLE/rows/100:199/JSON    # Next 100 rows

Default without rows: returns first 10,000 rows.

Output format

Append format as the last path segment:

/TABLE/.../JSON
/TABLE/.../XML
/TABLE/.../CSV
/TABLE/.../EXCEL

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AQS Data API (Separate System)

For more granular air quality data, EPA also provides the AQS Data API at:

https://aqs.epa.gov/data/api

• Requires: Free account at https://aqs.epa.gov/data/api/signup?email=YOUR_EMAIL
• Auth: Pass email and key as query parameters.
• Key endpoints: /dailyData/byState, /annualData/byState, /sampleData/bySite, /monitors/byState.

Example:

https://aqs.epa.gov/data/api/dailyData/byState?email=YOUR_EMAIL&key=YOUR_KEY&param=44201&bdate=20240101&edate=20240131&state=06

Notes

• Table and column names are case-insensitive in the URL.
• The Envirofacts API returns all columns for a table; you cannot select specific columns.
• For joining data across tables, you must make separate requests and join client-side using shared keys (e.g. TRI_FACILITY_ID, REGISTRY_ID).
• Some tables are very large. Always use rows/ to limit results and paginate.
• EPA data updates vary by program: TRI is annual, AQS is daily/annual, SDWIS is quarterly.