When using a vent-to-outdoor system, the Environmental Protection Agency (EPA) must be satisfied that the contaminated air being emitted to the outdoor environment, and the equipment used, is in compliance with current standards. This can be a lengthy process involving permit applications, testing, equipment evaluations, and regulatory paperwork. You can usually avoid the EPA altogether by using an engineered filtered fume extractor that does not emit pollution to the outdoors at all (e.g., Purex, BOFA, or Filtrabox engineered fume extractors).
