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U.S. Response: Health Officials Release Ventilation Security Guidelines By Mike Nartker “These guidelines offer practical advice to building owners, managers and maintenance staffs on the steps they can take to protect their ventilation systems,” Health and Human Services Secretary Tommy Thompson said in a press release. “This new guidance is an example of the many steps we have taken since last fall’s terrorist attacks to strengthen our capabilities to protect public health.” The new guidelines, created with the assistance of the Centers for Disease Control and Prevention’s National Institute for Occupational Safety and Health, outline several ways building owners can prevent terrorists from gaining access to ventilation systems and related equipment. One of the most important security measures is preventing terrorist access to openings that take in outdoor air, because a terrorist can use an intake to spread a contaminant throughout the ventilation system of an entire building, according to the guidelines. Intakes located at or below ground level are at the most risk, since many chemical, biological or radiological releases that occur at ground level would stay there, the guidelines say. The guidelines recommend that outdoor air intakes either be moved to less publicly accessible parts of a building or be extended to a height of at least 12 feet to keep them out of reach. A well-monitored security zone should guard outdoor air intakes, the guidelines say. Building owners should prevent access to mechanical areas that house ventilation system components, including filters, air-handling units and ventilation system controls, according to the guidelines. Public access should also be tightly controlled for building technical information, return air grilles and rooftops — where air intakes and ventilation system equipment might be located. The guidelines recommend limiting access by outside personnel and installing security measures such as cameras and guards at areas vulnerable to terrorist attack. “Difficult-to-reach outdoor air intakes and mechanical rooms alone may not stop a sufficiently determined person,” the guidelines say. Entry and Storage Areas To prevent the spread of any released contaminant, several entry and storage areas within a building — such as lobbies, loading docks and mailrooms — should be physically isolated, the guidelines say. “Lobby isolation is particularly critical in buildings where the main lobbies are open to the public,” they say. Ventilation systems for entry and storage areas should also be isolated and kept at a negative air pressure in relation to the rest of the building, but at positive air pressure related to outside, they said. Security checks should screen people and packages attempting to enter a building through a lobby, according to the guidelines. Filters To help prevent contamination while improving the general air quality of a building, owners should monitor and improve air filter effectiveness, the guidelines say. Particulate air filters that can help prevent against a biological or radiological attack are not effective against a chemical weapons attack, which would involve gases. Instead, adsorbent filters — which use sorbent-type materials such as activated carbon — can better protect against a chemical attack, the guidelines say.
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