Secondary emissions means emissions which occur as a result of the construction or operation of a major stationary source or major modification, but do not come from the major stationary source or major modification itself. For the purposes of this chapter, “secondary emissions” must be specific, well-defined, and quantifiable, and must impact the same general areas as the stationary source modification which causes the secondary emissions. “Secondary emissions” includes emissions from any offsite support facility which would not be constructed or increase its emissions except as a result of the construction or operation of the major stationary source or major modification. “Secondary emissions” does not include any emissions which come directly from a mobile source, such as emissions from the tailpipe of a motor vehicle, from a train, or from a vessel.