What are fugitive emissions?

Fugitive emissions are those that do not pass through vents, stacks, or other openings that are designed to vent emissions. Knowing if an emission is fugitive or non-fugitive is important for permitting, because non-fugitive emissions are always counted to determine if a source exceeds major source thresholds, while only certain fugitive emissions are counted.

EPA says that emissions that are actually collected are not fugitive emissions. For example, when a source is subject to a national standard that requires emissions collections, those emissions are not considered to be fugitive.

Where emissions are not actually collected at a particular site, the question of whether the emissions are fugitive or nonfugitive is made on a case-by-case basis by the permitting authority. EPA has stated that if other sources are using a certain kind of collection technology, then it presumes collection of emissions from a similar pollutant emitting activity is reasonable, even if that activity is located within a different source category.