The National Academy of Sciences, National Academy of Engineering, and Institute of Medicine inaugurated a study shortly after Sept. 11 to provide recommendations for combating terrorist threats. The report,Making the Nation Safer: The Role of Science and Technology in Countering Terrorism, is now available.

The report includes several measures in which the HVACR industry can contribute to the safety of individuals in facilities.

Toxic chemicals and other materials “provide a wide range of potential terrorist weapons for attacking targets of high value and visibility and for grabbing media attention and causing public panic,” the report notes. However, “We are not without resources for countering these threats: our current capacity to respond to chemical attacks is substantial.”

The document states, “The most plausible use of chemicals as weapons is in attacking aggregations of people in enclosed spaces,” such as federal buildings, high-rise office buildings, and airports.


“Every industrialized country is heavily reliant on chemicals; the United States is no exception,” the report says. So toxic chemicals are readily obtainable, and they can be introduced into a facility in various ways.

Sensors are identified as a primary means of preventing or minimizing the impact of a chemical or biological attack.

HVACR-related applications include sensors installed in ventilation systems that are capable of detecting deviations from normal and monitoring for chemical and biological agents. These sensors could then be used by building control systems to initiate a rapid shutdown of the ventilation system.

“Sensors are often designed for use in specific environments and to be selective for only one or two chemicals,” states the report. “Yet because there is a spectrum of possible threats, sensor systems are needed that can detect a large number of possible chemicals.”

One recommendation is that broad-based research should look for promising new principles on which better sensors might be based. Another is that a new program should be created to coordinate research and development, with the federal government overseeing testing and verification.


Regarding air filtration, “Research is needed to identify more effective technologies for removal of contaminants from different media,” including indoor air. The report indicates that HEPA (high-efficiency particulate air) filtration may be used for contaminated air.

It is recommended that universities, companies, and federal agencies work together to improve existing filter technologies and develop new ones for removing contaminants from air.


“Buildings at risk include key symbols of American wealth and political power such as the U.S. Capitol building, the White House, and the New York Stock Exchange. They also include high-rise office buildings, such as the Empire State Building, the Sears Tower, and the Transamerica Building,” says the document. Enclosed stadiums may also be targets.

“One way to prevent HVAC units from becoming the entry point for toxic agents is to restrict access to the outdoor air intakes and fan rooms,” it is noted. In existing buildings, this is more difficult, but “in new buildings, outdoor air intakes can more easily be protected.”

Filters that can remove “biotoxins and chemical toxins are available, but they are costly to install and operate.” However, “Filters to remove just biotoxins (e.g., anthrax) can be installed and operated; these might be a reasonable compromise.

“A better understanding of air movements and mixing in HVAC systems could lead to improved designs for lowering vulnerability to toxins.”

Further recommendations include research to determine how different toxins might be distributed, controlled, or filtered by the air-handling and circulation systems of buildings and stadiums. This research program, says the report, could be conducted by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).

Publication date: 07/08/2002