EPA — U.S. Environmental Protection Agency · Rate Limits

Epa Rate Limits

The U.S. EPA operates several distinct API surfaces, each with its own rate-limiting regime. The Air Quality System (AQS) Data Mart caps clients at 10 requests per minute with a recommended 5-second pause between calls and a per-query row ceiling. The Clean Air Markets (CAM) easey APIs enforce a per-key 1,000 requests/hour quota plus a 15-minute single-request timeout and 500-row page maximum. The Envirofacts REST data service does not publish an explicit per-second cap but rejects queries that fail to complete within 15 minutes. ECHO, FRS, ATTAINS, How's My Waterway, and most other open Envirofacts- fronted services are public and unauthenticated; reasonable use is expected. Several authenticated surfaces (Grants, FRS Submit, e-Manifest production) require credentials issued by EPA program offices and apply program-specific throttling.

Epa Rate Limits is the machine-readable rate-limit profile for EPA — U.S. Environmental Protection Agency on the APIs.io network, conforming to the API Commons Rate Limits specification.

It captures 11 rate-limit definitions, measuring requests_per_minute, seconds_between_requests, rows_per_query, parameters_per_request, and requests_per_hour.

The profile also includes 6 backoff/retry policies defined and response codes documented for throttled, quotaExceeded, requestTimeout, and serviceUnavailable.

Tagged areas include Rate Limiting, Government, and Environmental.

11 Limits Throttle: 429 Quota: 429
Rate LimitingGovernmentEnvironmental

Limits

AQS Data Mart — request rate account/key
requests_per_minute · minute
10
AQS documents a maximum of 10 requests per minute, with a 5-second recommended pause between requests; clients must await completion before submitting the next.
AQS Data Mart — interval between requests account/key
seconds_between_requests · second
5
Minimum 5-second pause between successive requests.
AQS Data Mart — per-query row ceiling query
rows_per_query
1000000
Queries returning more than 1,000,000 rows are discouraged and may be terminated.
AQS Data Mart — parameter codes per request query
parameters_per_request
5
Maximum of 5 AQS parameter codes per request.
Clean Air Markets (easey) — request rate account/key
requests_per_hour · hour
1000
Default per-key rate limit across all CAM streaming, emissions, facilities, accounts, and CAMD services.
Clean Air Markets (easey) — request timeout request
minutes_per_request · minute
15
A single CAM API request will time out after 15 minutes.
Clean Air Markets (easey) — page size query
rows_per_page
500
Maximum 500 rows per page for paginated CAM endpoints.
Clean Air Markets (easey) — streaming UI download request
rows_per_download
1000000
1,000,000 record maximum for streaming services UI downloads; programmatic API has no record cap.
Envirofacts Data Service — request timeout request
minutes_per_request · minute
15
Envirofacts queries that fail to complete within 15 minutes are aborted; use pagination to stream large result sets.
ECHO Web Services — query ID lifetime query
minutes_qid_valid · minute
30
ECHO get_facilities returns a query_id (QID) that is valid for roughly 30 minutes; subsequent get_qid / get_map / get_download calls must reference it within that window.
How's My Waterway, ATTAINS, FRS Query, e-Manifest, Insect Repellents, ELG Search IP
varies
not publicly documented
These public services do not publish a hard per-IP cap. Reasonable, well-behaved use is expected. Heavy scraping may be rate-limited at the edge by api.epa.gov or data.epa.gov.

Policies

ApiKeyRegistration
AQS requires email-based registration that returns a key by email. CAM requires a key requested via the CAM API Portal. api.data.gov fronts other EPA APIs with its standard X-API-Key sign-up flow (1,000 requests/hour default).
ExponentialBackoff
On 429 or timeout responses, retry with exponential backoff. The AQS docs recommend waiting for one request to complete before issuing the next; CAM recommends honoring Retry-After.
Pagination
Envirofacts pages via path-segment ranges (`1:100`). CAM streaming and v2 endpoints page via offset/limit query parameters. Always page large extracts rather than relying on a single oversize query.
BulkDownloads
For program-wide extracts, prefer the agency's bulk downloads (ECHO Exporter ZIPs, AQS pre-generated annual files, GHGRP downloads) over hammering the live APIs.
PrimacyAndStateData
Several program APIs reflect data forwarded from state primacy agencies; freshness varies by program (AQS data can lag 6+ months from collection).
AuthenticatedSubmissions
Submission APIs (FRS Submit, e-Manifest, Grants) are credentialed via NAAS/CDX and apply program-specific concurrency and throttling on a per-account basis.

Sources