On this page
Read three separate time fields
An annual dataset can be released after the period its underlying data describes. A webpage can also be updated without replacing the listed factor file. The activity record has its own dates. Keep these fields separate in a factor-source log.
Use the observed EPA listing carefully
On the research pass dated 10 October 2026, the EPA hub page showed a January 2026 webpage update while listing the 2025 factor release. That observation does not establish a factor dataset titled 2026. Inspect the actual downloaded file before naming its version.
Retain the useful dates
| Field | Purpose |
|---|---|
| Activity period | When the activity occurred |
| Factor data/release version | Which factor file and coverage were used |
| Access date | When the analyst checked that source |
| Restatement date | When a prior result changed |
Avoid silently mixing releases in a trend
A factor update can alter an emissions estimate even if activity is unchanged. Document whether both periods use their original versions or a consistent restatement. A trend comparison should explain that choice.