BALTIMORE, MD — Although the National Hvacr Security Summit held here has ended, the debate on system safety, contractor liability, and technical improvements continues.

The summit, cosponsored by The News and the Air Conditioning Contractors of America (ACCA), brought together a blue-chip panel of industry experts to discuss what contractors and building operators can do to minimize the risks of air-handling systems being used for chemical or biological attacks (“Examining Building Security,” The News, Jan. 28). Many of the speakers who were asked follow-up questions at the conclusion of the summit found there was no time to answer all of them at the event. But several of the participants contacted by The News discussed questions about building access, the shutdown of hvac systems in the event of an attack, and the containment of biological agents.

More information will undoubtedly surface in the weeks to come. Those in the hvacr trade are certainly asking a lot more questions.


While no system or method of containment is guaranteed to be 100% effective, there are ways to minimize the threat of biochemical attacks, according to expert panelists at the summit. Methods discussed included preventing such attacks before they begin by limiting access to information and profiling company employees in order to determine if they might pose a threat to building security.

Michael Chipley, principal engineer and director of Marketing and Sales of UTD Technologies, said limiting the flow of information is a sound first step, but it’s not foolproof.

“Information and data security has already been locked down by many agencies and companies,” he said.

“The EPA took many sites that provided spill and containment contours off-line; many companies took organizational charts and geographic maps of facilities off-line, etc.,” he continued. “The difficult question is, how much information should the general public have access to that befits an open society and the sharing of relevant community information (water quality, toxic sites, chemical accident zones, etc.) that may prove valuable to terrorists?

“Information access can always be reduced or restricted, but that only requires an increase in the level of surveillance/recon a terrorist must do for planning purposes. The information is usually out there and can be found; we just shouldn’t make it easy for them.”

Kent Ferguson is director of DAC Services/STA United, a provider of employee background checks and substance abuse testing. He was asked whether a good screening process would have brought to light any terrorists prior to the Sept. 11 attacks.

“That is difficult to determine,” he said. “If the individual did not provide fraudulent information and there was nothing in their past that would raise a red flag (Social Security number was valid, no criminal history, employment history checks out, etc.), then you would have no way of knowing.

“Implementing a thorough screening program increases your chances of detecting fraudulent information and shows due diligence if you are challenged in a court of law. Increasing your screening procedures is not a fail- safe to every situation, but you are in a much more defensible position if something does happen.”

The Fair Credit Reporting Act (FCRA) requires anyone requesting a consumer report to disclose the type of report and obtain the individual’s written release, Ferguson added.

“I’m not an attorney, but I would suggest that the company implement a new company policy requiring that the new reports will be a condition of employment for existing employees as well as being required of new employees,” he said. “They will then need to develop a disclosure-and-release form for all to sign before ordering any reports. Of course, a discussion with legal counsel is advised.”


In the event of a biochemical attack, opinions vary as to how much outside air should be shut off and how much should be used to keep a constant flow of fresh air.

Barney Burroughs, former president of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and now an outside director of Environmental Design International, Ltd., gave his thoughts. “The initial ‘sky-is-falling’ recommendation that was on the street immediately after the bioterrorist incidents was to simply shut down the outdoor system. This response was coming from folks who are naive about building operation,” Burroughs said.

“Most buildings do not even have separate, autonomous outdoor ventilation systems, so the outdoor air cannot be shut down without the shutdown of the total building air-handling systems,” he continued. “To attempt to seal off outdoor air during system operation could possibly have disastrous impact on the ductwork. If the systems can be independently shut down, what is the impact on air balance without thorough understanding of the interface with other building systems, such as the exhaust system? The far more important consideration, as mentioned above, is the interface between the hvac system and the exhaust system(s) of the building.”

Joe McCarty, engineering team leader for the U.S. Army Corps of Engineers, offered his perspective: “Shutting down the hvac system is, and will likely remain, controversial. There is not a short or easy answer.

“It is true that for a typical building under a biochemical attack, by the time the building engineer or other responsible party with access to an ‘off switch’ realizes what is happening and reacts, it is likely too late for shutting down the hvac system to be effective.

“However,” he continued, “if the hvac system is shut down in anticipation of an attack due to warnings, nearby attacks, or similar, it will at least eliminate the hvac system from bringing the agent into the building from the exterior or from distributing the agent throughout the building.

“Our bottom-line position,” McCarty said, “is basically to provide the capability to shut the hvac system and exhaust fans off, but it is critical that the operation of the shutoff switch be an integral part of the emergency operation plans for the specific facility, and that clear direction and training be provided to the responsible occupant.”

McCarty also addressed the need for a sensor system that could detect the presence of a biochemical agent and automatically shut down the building’s hvac system. “To be effective, the sensor must be able to identify the agent — at least the presence of an agent — in the airstream and then close dampers, shut off fans, and initiate other appropriate actions before the contaminated air is distributed to the space.

“There is a role and a real need for good, effective sensors for biochemical protection in hvac systems,” he said. “Automating the stopping and starting of exhaust fans, dampers, and air-handling units and alarming the building occupants are obvious advantages. However, the sensors must be affordable, with reasonable maintenance requirements as well as being accurate and reliable.

“Over the next several years,” he concluded, “I expect to see a variety of products designed to meet this need. I hope that there will be a commercial standard developed to measure effectiveness.”


The most common word in biochemical threats is anthrax. Some companies have made claims that the anthrax bacteria and/or its spores can be contained or “killed.” Summit panelists attacked this topic from several different angles — starting with UVC light (ultraviolet light in the C band) and its ability to kill certain biological agents.

Forrest Fencl, president and ceo of Steril-Aire, Inc., said, “A recent Penn State study concluded that very high dosages of UVC would be needed to kill anthrax spores. It is important to note, however, that no actual testing was performed in this study; rather, the researchers did mathematical extrapolations based on existing anthrax studies, one of which dates back to the 1930s.

“Current concerns center around aerosolized anthrax; most of this existing data is derived from static, surface-killed spores contained in petri dishes or mounted on slides. The slide-mounting process creates microbe clumps and requires an oily base to keep the microbes in place. These conditions leave more than 50% of the anthrax microbes unexposed while drenching the spores in a UVC-absorbing material, making them extremely difficult to irradiate. Therefore, extrapolations from this data can hardly be used to predict the dosages required to destroy aerosolized microbes,” he said.

“In a separate test currently underway, surrogate spores were aerosolized and then tested in place of the spore formed from a depressed bacillus anthracis. Results of this testing indicate that the energy required for a kill is actually quite low. Once the test protocol has been accepted, testing of actual aerosolized anthrax spores will follow. Until this testing is completed, no one can make absolute claims about the exact UVC dosages needed to kill aerosolized anthrax.”

Charlie Seyffer, marketing specialist for Camfil-Farr, discussed the effectiveness of UVC and multi-mix media against biochemical agents. “Biological agents in the form of bacteria are large,” he said. “Ninety-eight percent are over 1 micron in size. Bacteria is easily removed by ASHRAE-rated filters (85%, or MERV 13 or better) as long as you are moving the air through the conditioned space by operating the air-handling system.

“Viruses are very small, milli-microns in size. They commonly attach themselves to other, larger particles and are often removed through the capture of the larger contaminants in the air filtration system. The majority of viruses also require a constant host to survive (nutrient), and their lifespan outside of a host is usually brief. Most viruses are transmitted by touch or through the release of droplet nucleli (coughs and sneezes).

“UV light, both natural and that introduced by technology, has a debilitating effect on the viability of these organisms. The key to UV light is the amount of time the organism is exposed to the UV light. The longer the period of time and the stronger the radiance of the light, the quicker the organism will be rendered harmless.

“Particulate filtration, from a standard home furnace, fiberglass throwaway to the high-technology HEPA filters used in hospital operating suites, remove particles based upon their use of a specific form of filter media. A HEPA filter is designed to remove 99.97% of all particles 0.3 micron and larger. A standard fiberglass throwaway will remove 99% of all particles over 10 microns in size, but has virtually no efficiency on submicron-size particles.

“When considering the removal of bacteria, use at least a MERV-13 filter. When the prime consideration is the removal of viruses, use at least a base level of a HEPA filter, 99.97% at 0.3 micron. In buildings with standard concerns, use a MERV-13 filter and move air through the filters (fan in the ‘on’ position instead of cycling based upon temperature demands). UVC light in close proximity of the air filter bank can assist in killing the viable items captured by the air filters.

“Carbon is designed to remove gaseous contaminants through the process of adsorption. In hvac applications, it is not unusual to have up to 90 lb of carbon for 1,200 to 2,000 system cfm, in one 24- by 24-in. opening. Carbon does not adsorb all gases. Carbon may be treated to increase its efficiency for removing a specific contaminant, or to enhance its efficiency where it may otherwise have a low affinity to removing a specific contaminant.”

Another product mentioned in the containment of contaminants is the ion generator. Brian Monk, vice president of sales and marketing of Circul-Aire, talked skeptically about this product.

“Although the use of ion generators in some commercial applications, such as tobacco smoke reduction and odor control in restaurants, has been successful, the use of this technology in an emergency or toxic air application is not recommended,” he said.

“An ion generator’s ability to successfully eliminate all potential contaminants released during an event are questionable. There is no technical evidence available that can substantiate an ion generator’s ability to reduce high concentrations of either chemical or biological contaminants to safe levels. Moreover, bi-polar ionization systems cannot provide the assurance that the system will be fully operational when required since the series of tubes inside an AHU require power to function.

“During an instantaneous release, the contact time required to remove all of the chemical or biological agent is very high, and as such the ion generator will not be able to adequately reduce the contaminant within the ductwork. Therefore, an introduction of ions into the protected space will be required to attempt to ‘complete’ the filtration process. As a result, the contaminant will be allowed to enter the space, and this alternative is not recommended for life-threatening concentration levels.”


So, how is a product tested for its effectiveness against anthrax? Gregg Burnett, vice president and general manager of Dust Free, gave his thoughts.

“We initiated our testing by asking some of our larger commercial UV accounts what test data would be the most useful to them in dealing with bacteria spores,” he said. “With that information in mind, we contacted some consultants in the IAQ field for recommendations in selecting a lab that has experience in performing tests with microorganisms.

“After selecting the right lab, we discussed how Bio-Fighter UV lights are normally installed in a commercial air handler and a protocol was developed that would resemble the real-world application our customers were looking for. We are looking at other protocols that would address other applications such as air mixing devices and various filter medias.”

Stephen Zitin, founder and president of Bioclimatic, Inc., said his company has developed an IAQ analysis program that covers many of the topics relative to safe and clean indoor air. “We have designed an Excel-based modeling program to assist consulting engineers and designers in determining optimum ventilation rates in combination with air cleaning to achieve acceptable IAQ,” he said.

“Achieving acceptable IAQ is a complex issue; there are numerous variables that must be considered. These include but are not limited to ventilation airflow, contaminant sources, air-cleaning efficiency, filtration, and operation/maintenance of the hvac system. Acceptable IAQ takes into account occupant comfort as well as safety.”

Robert Baker, chairman and ceo of BBJ Environmental, discussed the ramifications of claims that companies make about products that “kill” anthrax.

“If a company placed a statement [about anthrax-killing product] on their website or in their advertising materials, the Environmental Protection Agency might well ask them to remove that statement and if they did not, bring an administrative proceeding against them,” he said.

“The legal fact is that EPA has not yet adopted an official regulatory position on what organisms have ‘the same basic chemical makeup as anthrax.’ Until they do, they are unlikely to allow such statements as these.

“The real problem here is that they are probably not talking about the spore form of anthrax, which is the infective agent of concern. They are, in all probability, talking about the live or vegetative form, which is not what we are trying to protect ourselves from. As a result, the net result of the conversation is that someone who is given that type of answer is probably misled in that they are looking for some level of protection and are unlikely to get it based on the information they are getting.

“I like to use the case of the editor in Florida who opened the envelope containing anthrax spores, was infected, and died. He could have sprayed his entire office with the most effective product in the world before opening that letter and the outcome would have been the same.”

The question of treating the mail in government buildings was also raised at the summit.

“This is being handled by the Post Office and not by the individual agencies — at least not the U.S. Army Corps of Engineers,” McCarty said. “I do know that most of the mail I get has been ‘irradiated,’ but I’m not sure exactly what that includes and if that is anything more than just a temporary and/or local procedure. I anticipate that in the future, most new Department of Defense facilities will have ground-level mailrooms with separate entrances and separate ventilation systems.”

Publication date: 02/11/2002