Got it, thanks. Bottom line is that these certifications are used as more of an administrative tool for properly regulating facilities that have higher, Title V-level PTEs but that are, in reality, operating more like minor source facilities. Makes sense.
Interesting to hear, though, that working with companies/facilities to lower emissions isn't standard practice for air quality agencies. That's quite different from my experience administering Section 404 of the Clean Water Act. At the Corps, we work with applicants to reduce/offset impacts to aquatic resources by applying what's known as the
mitigation sequence ("avoid, minimize, compensate"). Permit applicants must first demonstrate that they've
avoided impacts to the maximum extent practicable. We next explore measures to
minimize remaining unavoidable impacts through project modifications and permit conditions. After avoidance and minimization have been fully explored, applicants are required to
compensate remaining impacts through compensatory mitigation requirements (e.g., restoring an aquatic resource on- or off-site).
If air quality agencies aren't working with applicants to lower emissions, I guess I'm wondering what types of conditions get added to air permits to mitigate environmental damage? I suppose, for example, the permit conditions might stipulate what times of day emissions could occur (e.g., to ensure emissions don't go above a certain level at any point in a given area), right? What sort of influence do air quality agencies exert through permitting to promote real-world environmental benefits?