I work with strong solvent glues a lot so, years ago, I designed and built a custom industrial-grade fume booth. I also wanted it to double as a spray booth.
If you're exhausting any sort of flammable vapors you need a spark-proof fan. When I built my booth these were not easy to come by and they often cost a small fortune. It's my understanding regular fans have exposed motor components that can ignite vapors in the exhaust.
Also, keep in mind fans are designed to push air rather than pull it. Thus, your fan needs to be mounted where the air is collected and not at the other end of a long exhaust hose. Otherwise, you'll lose a great deal of efficiency.
I ended up choosing a marine bilge blower for my booth. It's powerful but I still doubled up and used two of them. (IIRC, they move 450 cubic feet per minute each.) They're loud though and run only on 12 Volts DC. They also draw 6 Amps each so that requires a heavy-duty power supply.
I even added special circuitry that prevents sparks when the fans are turned on and off. When a motor shuts OFF it creates a large reverse voltage spike. This can cause arcing inside your relays. Thus, spark-suppression is also needed in your control wiring.