Secure Buildings: Pre-Event Advice – Long-Term: Separate HVAC Systems
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Last Updated
April 27, 2005

Pre-Event Advice – Long-Term

Do not mix air from mail rooms and other high-risk locations into the rest of the building.

Click here to view an animation of how the ventilation system spreads contamination.

Mailrooms, delivery areas such as loading docks, and areas with public access are the most likely locations for introducing toxic substances to a building. If the HVAC systems for these areas do not mix air into the rest of the building, the spread of the agent will be greatly reduced. Mixing into the general building air can be prevented either by providing a separate air-handling unit for these areas, or by eliminating return air for these areas and exhausting them directly. (Contamination may still spread along hallways, etc., but this will be much slower).

Consider adjusting the HVAC supply and exhaust so that the high-risk areas are slightly de-pressurized with respect to the rest of the building, so that air will flow from other areas into the high-risk areas rather than the other way around.

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