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.

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

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

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.