I've been privileged  to see Vinod Daniel's work on the use of inert gas
chambers for fumigation, and it does work. Like freezing, inert gas
fumigation has no residual effect, and you still need to provide adequate
storage and isolation, plus track down the pests at their point of access
and block that, etc. But it's an infinitely better solution than fumigation.
Sally Shelton
Collections Conservation Specialist
San Diego Natural HIstory Museum