This article is an editorial. There is little from science in this article, but a lot from common sense. It appears to me that common sense is exactly what we need during times like these. So, lets ask some questions to guide this discussion.

First, do terrorism and building automation systems belong in the same sentence? Recent advertising by a gas phase filtration manufacturer and some UV products suggest that devices can be added to protect a building's intakes from attack. The ads tend to play on the public anxiety that has developed as a result of the mail-borne anthrax attacks in October. We are all anxious about the possibility of renewed attacks, but how does one evaluate any proposed defense against this threat?

Is there any way to address this serious issue without raising the eyebrows of liberal-minded people who would insist that everyone must be protected from every conceivable terrorist threat? Do we need to spend many billions on systems and countermeasures that are unlikely to protect anyone, without consideration of what the most likely targets could be?

We can run around in Biohazard suits and feel reasonably safe against biological and chemical attacks. But then, we would have to get doorways and elevators modified to handle the same volume of people in "bubble" suits. They also make it difficult to drive in anything smaller than a UPS van.

We really need to be asking ourselves: "What makes sense?"

Building Automation Systems (BAS) and ventilation systems are designed primarily to keep its occupants comfortable. They were not designed for structures expected to be on the front lines of a battle using unconventional weapons. Some may have been fitted with projectile resistant glass or glass coatings (i.e. U.S. embassies abroad or Dade County (FL) hurricane code requirements), but I would guess that only a few military structures in this country have much in the way of fixed, HVAC systems protection from chemical or biological weapons (CBW).

Commercial ventilation systems are a potential means of airborne "weapons" delivery, but also a potential defense since they have the capability of isolating areas from CBW with space differential pressure control. The BAS can then be considered a means of using the capabilities of the ventilation system by being programmed to quickly respond and mitigate an attack. If we combine those thoughts with some realistic evaluation of the level of risk to your building's occupants from the threat, then I think we are finally headed in the right direction. We may find reasonable answers to our questions.

With bio-terrorism, and especially attacks with chemical agents, it seems to me that one of the greatest threats is using the ventilation system to distribute an aerosolized chemical agent, airborne infectious bacteria or virus. This multiplies the effectiveness of the attack and uses the system against the occupants. Isn't the easiest and simplest thing to consider first, is to deny this method of distribution to potential attackers? Makes sense to me.

BAS are typically programmed to automatically respond to fire emergencies and smoke control systems, plus have the potential to account for a range of other life safety threats. A logical one to consider now is CBW attack. End users could adjust the way they're using a BAS to accommodate a threat from bio-terrorism by allowing a manual "panic button" approach. This would simply shut down fans and all operable dampers and prevent dangerous agents from migrating through the air distribution system of a building.

I am sure the military has had sensors capable of detecting most chemical and radiation threats for many years. To employ them in a commercial setting appears to be difficult to justify, impractical and very expensive. A biological threat is much more difficult, if not impossible, to detect or sense automatically with remote instrumentation, then warn the occupants.

I would think that existing smoke control components (e.g. smoke and fire/smoke dampers) are the primary means of effecting the compartmentation of a building. The physical manifestations of such a system would be very similar to existing smoke control systems. Some would require everything to close or shut down.

Another scenario would adapt an existing smoke control system to provide "means of egress" with differential pressure barriers, possibly even with areas of refuge, should the structure be difficult to evacuate. These would operate fans and dampers so as to provide areas isolated by differential pressure using airflow controls, the same way airborne infection control is supposed to work in hospitals. Without a sensing element to automatically detect every possible biological threat and harmful chemical agent, it would require manual activation and permanently installed instrumentation to provide the needed control inputs.

Few non-governmental facilities have considered military-style CBW defensive systems. These few may have reason to feel that the threat is sufficient enough to require a drastic and immediate response. It may be more troubling to those managing and occupying the largest and most difficult structures to evacuate, or to those housing symbols of U.S. power or ideals. This is merely a logical deduction.

There are several things that commercial buildings might consider to improve the survivability of their occupants in an attack, using existing HVAC system components. Applying sensitive and accurate sensors to prove airflow velocity and direction can allow the automated controls to create reliable and safe areas of refuge or protected avenues of egress, after an attack is determined (or suspected). Attacks are likely to be invisible, odorless and otherwise undetectable, thereby heightening the terror of potential future victims.

From my personal perspective, I would first determine how effective high tech filtration and UV technologies are reported to be, and the range of threats they may address. Where appropriate, both eradication and filtration are easy upgrades to implement in most systems, by professional contractors. However, fan capacities will be the most affected when additional pressure losses from high-efficiency filtration are introduced into any system originally designed without them.

Any combination of commercially available HVAC equipment (e.g. BAS controls, filters, etc.) cannot keep building occupants totally safe. Remember that these are static defenses that can be easily circumvented. A determined attacker may choose from a variety of delivery means or systems. Only a few may consider the use of the building's ventilation system to multiply the effectiveness of the attack. Not all types of agents can use or would need it to be effective. A "panic button" used to shutdown to compartmentalize a structure or isolate specific areas are approaches that may be the most effective and the least costly for the average office structure.

Some customers may be willing to pay any cost for additional products and controls that protect building occupants, but I believe the logic in that depends on the level of the threat and the risk provided by the structure. Those in highly visible and politically "attractive" structures should be more concerned than your average low-rise offices and industrial parks.

Finally, many more ideas about the implementation of possible control scenarios will be developed in the future, due to the increased attention from the media and subsequent discussion. I doubt that there will be much change in the nature of existing or new products specifically to counter a bio-terrorist threat. There may be some exceptions, primarily in the government, the military and with government contractors, but doubt that it will impact the vast majority of public and private buildings - unless things get very bad, very quickly.

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