Is it acceptable to have an individual vent for a shower that does not exhaust to the roof? In the case of the new work on my home, the exhaust pipe simply runs through a hole in the ceiling of a closet and terminates there-I was told it was only for the shower, but am not sure how the toilet and sink are vented. I believe it pulls from a small space above a closet on the main floor which may be indirectly pulling through the attic.

I tried to read through the Massachusetts plumbing code, but wasn't sure I got it right. It seems to say all vents should either vent to the roof, or connect above the fixture into the venting system, meaning that my installation is improper. Thanks!

Vent has to terminate above the roof no matter what City you live in. Have it extended or combined with existing vent. Unless you do so, it remains to be a health hazard.

If your state allows air admittance valves, the vent can terminate in an accessible, ventilated attic without exiting to fresh air or connecting to another vent.

Call your local code office.

If the vent terminates inside your house you have a direct connection to the city sewer that allows sewer gas to enter your home. Sewer gas is a health hazard to your family and the methane content makes it explosive,
Extend the vent to the attic and revent back to a existing roof vent. Good luck, Tom