Environmental Protection Agency National Emission Inventory (NEI)

Data Category

Facility compliance and enforcement

Spatial Extent

United States

Chemicals

CAPs • HAPs

Provider

Environmental Protection Agency

Temporal Resolution

Annual Average

Update Frequency

Every 3 Years

Description

Compilation of air emissions estimates from various sources, including point sources like petrochemical facilities, transportation and fires. Data is compiled from other EPA emissions programs and from data provided by state, local and tribal agencies.

Potential Uses

• Find air emissions totals or trends for an area

Limitations

Point source emissions are self-reported by facilities to state and local agencies, which then report to EPA. Some states and local agencies don't require HAPS reporting, so EPA fills in HAPs data gaps using TRI leading to variable data quality among states. Reporting of start-up, shut-down, maintenance, and malfunction emissions is not currently required. Many emissions are modeled rather than measured, adding additional uncertainty.