A filtration system is arranged to safely vent a storage room into which a fog mixture is introduced. Venting the storage room reduces and/or prevents a substantial increase in the internal pressure of the storage room. To control the pressure differential between the storage room and the ambient air pressure, a venting manifold with an in-line duct fan is used, for example, to exhaust storage room air into the atmosphere. The exhausted storage room air is filtered to reduce the exfiltration of chemicals and/or other contaminants from the environmentally sealed storage room.