Know the CBRN Risks
Written by Stephenie Slahor
Chemical, biological, radiological and nuclear (CBRN) threats are real and homeland security must be ready for them. CBRN risks are no longer limited to government or mission-critical facilities. Philip Stearns, a Senior Associate with Malcolm Pimie, Inc., addressed the annual meeting of ASIS International in Anaheim, Calif. He explained that risk mitigation solutions must be developed for CBRN threats such as biological particulates (e.g. anthrax), chemical liquids or vapors (e.g. chlorine), and radiological particulates (e.g. dirty bombs).
The CBRN attack could be delivered by mail or parcels. According to Stearns, many buildings have inadequate control on deliveries or incoming mail. Also, CBRN contaminants could be introduced through an HVAC system so the agent is distributed throughout the building with the least dilution by fresh air. Or an agent could be released outside, but enter the building through an HVAC's fresh air intake.
Most buildings have easily accessible HVAC intakes, he pointed out. Even in buildings with not-so-accessible intakes, the agent could be released inside the building and spread via the HVAC system into other areas of the facility. Water supplies could be vulnerable to CBRN threats, too, in much the same way, Stearns added.
Even though the likelihood of such scenarios is relatively low due to the difficulty of obtaining CBRN agents and then distributing them, Stearns said crackdowns on other potential threats may be increasing the likelihood of CBRN attacks. Many governments are raising their awareness and planning efforts, he said.
The impact of a CBRN attack could be deadly and / or injurious to many people and there would be collateral damage associated with the contaminated building. Stearns noted there would be psychological impacts on the rest of the public, and economic impacts due to businesses closing or decreasing in their commerce because of the fear caused by the CBRN attack.
One of the first steps in planning protection from CBRN risk is to designate collective protection areas, Stearns said. These would be based on the number of people to be sheltered, the required floor or open space per person, and the availability of large, open areas, in buildings or outside, to protect a large number of people. Another point to consider in planning protection might be the use of a stand-alone building to be used by delivery persons, mail and parcel carriers, etc. so there is decreased access by non-employees into the actual building or facility.
Access to air intakes of the HVAC system must be limited. Such intakes could be mounted high on a wall or on a roof, in a restricted access area, or covered with security grates to prevent entrance. High Efficiency Particulate Air (HEPA) and Granular Activated Carbon (GAC) filters may be necessary as a safeguard against particulates. HEPA filters remove aerosols and microbiological agents, he said, and GAC filters remove CBRN agents in their gaseous or vapor form. Stearns added that a CBRN filter system does not eliminate risk, but it can reduce the impact of a CBRN attack.
In the event of a chemical attack, Stearns suggested shutting off any suspect return air intakes, turning on all exhaust and smoke removal fans in the affected area, pressurizing the stairwells with clean outside air so people can exit the building safely, and evacuating the building to a safe collective protection area at least 100 feet away.
For an indoor biological attack, Stearns advised closing all dampers and shutting down building systems, pressurizing stairwells with clean outside air, and evacuating the building, but separating the people who have been exposed to the biological agent so exposure is limited to them and so they can be treated first.
In an outdoor chemical or biological attack, a decision must be made whether to keep people inside. If the building is structurally sound and there are no immediate threats such as collapse or fire, it may be safer to keep people inside. They should go to their respective collective protection areas, but not use elevators to get there.
Windows and all internal and external doors should be closed, Stearns said, and all air systems, including exhaust, should be turned off. If the building has a CBRN filtration system, the building can be pressurized with treated air. The building can be later flushed with fresh outdoor air.
Stearns added that it is wise to have specific protocols in any emergency response plan for response to airborne CBRN threats, including how the HVAC system operates or is shut off in the various scenarios. There should be response training in CBRN-specific instructions. Vulnerable parts of buildings should have limited access. CBRN filtration systems must be maintained properly so they actually provide protection. Just as in other homeland security, preparedness is key.
Stephenie Slahor, Ph.D., J.D., writes in the fields of law enforcement and security. She can be reached at email@example.com.
Published in Tactical Response, May/Jun 2012
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