Protecting buildings against bioterrorism—review of guidance and tools

ASHRAE Transactions, Jan, 2007 by F.E. Yeboah, F. Chowdhury, S. Ilias, H. Singh, L. Sparks

ABSTRACT

Ever since the September 11, 2001, terrorist attacks and the subsequent anthrax incidents in the US, attempts have been made to thwart further attacks and other forms of terrorism. Attacks involving chemical and/or biological agents (CBA) are among the most dreaded because of the ease with which they can be produced and disseminated as well as their fatal potency.

Protecting buildings and built-in environments against bioterrorism or CBA attacks are key issues in homeland security. Unfortunately, the threat posed by chemical and/or biological agents is so complex that building professionals should be educated about what they are, possible scenarios of their release, how they may be detected, how buildings may be "immunized" against such threats, etc. Terrorists will try to cause as many casualties as possible, with high-occupancy structures such as commercial buildings being at elevated risk in any such CBA release. Building owners and building professionals should, therefore, have some level of understanding and appreciation of the dangers that such an attack poses. This paper reviews some of the necessary guidance and tools that are available for educating building professionals on protecting building occupants against CBA attacks.

INTRODUCTION

The 9/11 terrorist attacks and the subsequent anthrax incidents in the US suggest that much more effort is needed to protect buildings against attacks by chemical and/or biological agents (CBA). Buildings are attractive targets because of the high density of people in them at any given time and the fact that most people in the United States are known to spend about 90% of their time indoors in homes, schools, offices, etc. (EPA 1997).

In response to the fear, chaos, and destruction that followed the September 11 attacks, federal, state, and local authorities have issued safety and other protective measures to safeguard high profile buildings and facilities against CBA attacks. These include the use of concrete barriers, shatterproof windows and reinforced steel plates, and HVAC systems that are designed to prevent the circulation of contaminated air in the event of CBA attacks. Some private building owners and operators have also taken steps to increase security. In fact, building owners and building designers have abandoned the illusion that their buildings are "immune" against terrorist attacks and instead accepted the reality that these buildings are indeed vulnerable.

Unfortunately, not all buildings are well protected, and, hence, designers and owners may have to worry about more than mere moral culpability for the loss of life that ensues. They also face potential civil lawsuits, since September 11-style attacks against buildings are now foreseeable under the "Totality of the Circumstances" test (Pharr and Menzel 2005). Building owners and designers can no longer circumvent legal liability by arguing that a release of chemical or biological agents in a building's HVAC system was unforeseeable.

The Terrorist Risk Insurance Act (TRIA) has been enacted to insure, among others, commercial buildings against terrorist attacks. The Act is, however, restricted to the use of conventional weapons and attacks by foreign terrorists (RAND 2005). TRIA has an exclusion clause for domestic terrorist activities and attacks involving chemical, biological, radiological, and nuclear weapons. It is, therefore, incumbent upon every commercial building owner to find ways of preventing CBA incidents from occurring or reducing the impact of CBA incidents should they occur.

Several tools are available that can be used to help mitigate or reduce the impact of CBA attack. This paper reviews some of the guidance and tools that are available to educate building professionals on how best buildings may be operated or designed to protect them from CBA attack or to reduce the impact from such attacks. A discussion of some of the guidance that can be used during an outdoor or indoor CBA release will be made. This will be followed by an assessment of certain guidelines that are available for safe building design. Two main filter rating systems are very prevalent in the US--the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standards 52.1-1992 and 52.2-1999 (FEMA 2003). These are also briefly discussed. Finally, we also discuss the tools that are available for modeling the dispersion and transportation of CBA, with focus on zonal and computational fluid dynamic models.

GUIDANCE

Indoor and Outdoor Release of CBA

US Army Regulation AR 50-6, Nuclear and Chemical Weapons and Material--Chemical Surety, prescribes procedures, policies, and responsibilities for the Army Chemical Surety Program (DOA 2001). AR 50-6 stipulates that when evidence of a chemical leakage is established, the source should be located, isolated, and contained as soon as practicable. If the source cannot be located immediately, the facility should be closed, then continuously filtered and periodically monitored until the source is isolated or until low level monitoring indicates the source no longer exists (DOA 2001).