Saint Louis Park
It's the latter.
Q: If a location is revealed after Treacherous Fog (CORE 118) was revealed during the same quest phase, does the revealed location get +1 $ from the “When Revealed” effect on Treacherous Fog?
A: Yes. The “When Revealed” effect on Treacherous Fog creates a lasting effect until the end of the phase that affects each location in the staging area. This is different from Driven by Shadow (CORE 92) which uses the language “currently in the staging area” when it is revealed and only affects enemies and locations in the staging area at the time it is revealed.