Getting to this thread a little late, but anyway, every small laser I've seen has its own exhaust fan, running whenever the laser is. This is mostly because even without the extra inert gases, ,a ser cutting anything generates stuff you don't want in the laser cabinet, let alone in the shop. The only exception are the big bed cutters like the 2000W monster mentioned elsewhere, and they usually have other arrangements anyway.
If the laser has its own cabinet, it probably has a fan that keeps it at a negative pressure, meaning the gas would never get out into the shop except in an emergency, and that would be, well, an emergency. It would need to be considered whether that fan needs upgrading, but it won't be pulling out a whole room or shop. Likely they'd not need a new fan, just a plan and maybe sensors for that emergency Murphy situation.