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Air Emissions Inventories

How do the different parts of particulate matter (PM) fit together?

The various parts of PM in the NEI are related as follows.

PM10-FIL > PM25-FIL because PM10-FIL includes PM25-FIL
PM25-PRI = PM25-FIL + PM-CON
- This equation only applies at the process level.
- Because some sources only can report PM2.5 (due to test method differences), this equation does not apply to NEI summaries
PM10-PRI = PM10-FIL + PM-CON
- This equation only applies at the process level.
- Because some sources only can report PM2.5 (due to test method differences), this equation does not apply to NEI summaries
PM-FIL = Filterable PM above size 10
- These values are not required in the NEI and are therefore not complete in NEI releases
PM-PRI = Filterable + Condensible PM both above size 10

The best measure in the NEI of actual total filterable PM is PM10-FIL, since it includes PM25-FIL and PM-FIL (>10) is not complete. Similarly, the best measure in the NEI of actual total PM is PM10-PRI, since it includes PM25-PRI and PM-PRI is not complete.