The warnings came as U.S. Homeland Security officials revealed that Al Qaeda has detailed information about buildings and surroundings of such firms in New York, Newark, N.J., and Washington, D.C. The terror threat alert was raised to orange (high) in those areas.

New York Police Commissioner Raymond Kelly said police were advising owners or managers of other large businesses to safeguard their HVAC systems. The night of Aug. 1 he went with police counterterrorism and intelligence units to brief security directors of 13 major financial firms, asking many to heighten security on ventilation systems as well as on deliveries and visitors. "There was no time frame with the intelligence," Kelly said in a press conference.

Homeland Security Secretary Tom Ridge later noted that al Qaeda's information had been gathered over the past four or more years. The possible terrorist targets Ridge identified included the New York Stock Exchange and Citigroup sites in New York, including the Citicorp Center; the Prudential Financial Building in Newark; World Bank buildings in Washington, and International Monetary Fund sites in both New York and Washington. Officials also mentioned other institutions in New York, New Jersey and Washington, D.C., and the Bank of America building in San Francisco.

Raising Awareness

"The most significant new concern that has arisen as a result of these recent alerts is the likelihood that some of these individuals may have infiltrated or become employed in these buildings and have access and knowledge of what's in the building that an outsider would not," said Larry Spielvogel, chairman of ASHRAE's Presidential Ad Hoc Committee on Homeland Security.

Spielvogel is a consulting engineer from Philadelphia; his practice is primarily consulting on existing buildings. He reports generally mounting interest in system safety, "but more importantly we have increased traffic within the committee wondering what, if anything, we should do in light of this new information."

Spielvogel said a committee conference call was scheduled for August 9 to discuss it.

"We are planning a seminar and a forum at the ASHRAE meeting in Orlando in February 2005 to address not only changes that should be made in the report, but also what experience have we had with the recommendations we've made so far," said Spielvogel.

Have people done anything about the report? "Yes and no," he answered. It depends primarily on the extent of risk they perceive. "Related to HVAC, we're trying to raise the awareness of designers and owners to the kinds of issues they need to consider."

A spokesperson for the Building Owners and Managers Association - New York stated that members have been steadily improving the security and monitoring of their HVAC systems since the attacks of Sept. 11, 2001, and that after the Aug. 1 warnings, HVAC as well as other vulnerabilities have been rechecked and readdressed.

Reports Available

He said owners should lock up and limit access to building plans and HVAC systems. He also emphasized that air intakes need to be safeguarded and, where possible, moved to higher and/or less accessible locations.

Preventing access to outdoor air intakes is also recommended by the National Institute for Occupational Safety and Health (NIOSH) in its publication, "Guidance for Protecting Building Environments from Airborne Chemical, Biological, or Radiological Attacks."

Providing separate air exhaust systems for mail rooms and other high-risk locations and enabling building operators to quickly manipulate HVAC systems to respond to different types of attack are actions advocated by Lawrence Berkeley National Laboratory (LBNL) in its "Advice for Safeguarding Buildings against Chemical or Biological Attack."

Sidebar: Resources Detail More Ways To Protect Building HVAC