Detection and Identification of Airborne Hazards

And while detection systems of varying degrees of sophistication are available, it is important to understand that the higher the detection system sensitivity, the higher the likelihood of false alarms, and the "smarter" the unit is, the higher its cost, although that correlation does not necessarily carry through in relationship to accuracy or reliability. There are a few large, vehicular mounted systems which are designed using several integrated detection technologies and sensors that can provide an almost complete suite of detection capabilities.

In general, when contemplating detection and sensing devices and systems, it is recommended that you rely on the technologies, equipment and systems which have been developed for and tested by the United States military. Unlike conventional air filtration systems and filters, this equipment is specifically designed to effectively counteract the effects of CBRN warfare agents and is the only known solution to remove airborne toxins.

Perceptible warning properties
Many hazardous chemicals have perceptible warning properties, which provide a practical means for detecting a hazard and initiating protective actions in combat situations -- outdoors where protective gear is at hand. These warning properties make chemicals perceptible to highly-trained and experienced individuals; that is, the vapors or gases can be perceived by the human senses -- smell, sight, taste, irritation of the eyes, skin or throat -- before serious effects occur.

In reality, without proper training, it is extremely dangerous to rely on a civilian worker in an office building to accurately identify the smell of fresh hay or garlic as the toxic phosgene and arsine, respectively, or simply gardening day and someone's lunch. Toxic Lewsite, for example, smells like geraniums. An atrium plant could cause a stampede. What's more, many agents, such as PFIB, a form of GA, pure GB, CK and others, have very little odor or are totally odorless. In a civilian setting, commercially available military quality sensors should always be employed to detect and identify airborne hazards. Most reasonably well-equipped fire departments and first response vehicles have such devices and are as near as phone call.

Biological agents (bacteria, viruses, SEB and toxins such as botulism) are also imperceptible, and there are no "real-time" commercial detection devices that can determine their presence in the air in real time before the onset of human symptoms. Therefore it is currently unrealistic to base protective actions upon the detection of these agents.

In the absence of a perceptible warning property, such as odor, people must rely on observing symptoms or effects in themselves and others. This provides a practical means for initiating protective actions. Susceptibility to hazardous materials varies from one person to the next. The concentrations of these agents may also vary significantly within a building or even a room creating more of a hazard for some occupants than others.

Other signs of an airborne hazard may include seeing or hearing something out of the ordinary such as an explosion, the hiss of a rapid release from a pressurized cylinder, unscheduled dissemination of an unusual spray, abandoned chemical containers or spraying devices, numerous dead animals or insects in a concentrated area, and large numbers of people with common symptoms.

The only reliable protective measures which can be taken against imperceptible agents are those that are continuously in place (i.e., permanently installed on the building's HVAC units), such as the Hunter FFA Series CBRN positive pressure collective protection system. Properly installed in a building's HVAC system with necessary air handling and duct alterations to create Toxic Free Areas (TFAs), these advanced technology filters will provide protection from the affects of potentially deadly CBRN agents.

For the purpose of defining protective measures for buildings and protective actions, releases of airborne hazards are divided into two general categories-external, or outdoor and internal, or indoor.