The modern world of firefighting is a constant game of “cat and mouse” as our domestic world undergoes constant change and improvement. New building materials are created all the time and construction techniques continually change. However as these materials and methods change, they also conversely affect the very nature of the operating environment that a firefighter has to work under in an emergency situation.
Firefighters now face a dichotomy of threats in that they must respond to emergencies in buildings that could be hundreds of years old, creating one specific set of threat conditions, whilst in the next moment respond to a modern building fire with a completely different set of hazardous conditions. For example modern plastics/composite materials such as Nylon, Polystrene and Polyvinyl Chloride (PVC) will all degrade in a fire to yield noxious gases such a hydrogen chloride, hydrogen cyanide etc. as well as cancer causing particulate materials such as naphthalene and alpha-pyrene. Older buildings which may contain asbestos or lead containing materials in their construction pose just as much a risk to the firefighter if not more so. Again these risks are common to the firefighter in his or her daily operating environment and do not include the more exotic hazards encountered in other areas of the first responder domain e.g. CBRN or HAZMAT incidents.
During a fire, firefighters wear self-contained breathing apparatus (SCBA) to protect themselves against acutely toxic concentrations of combustion products. However after a fire has been extinguished, fire-fighters undertake overhaul, a phase when potential reignition sources are extinguished and site investigations begin. During this overhaul period, fire-fighters can be exposed to potentially harmful concentrations of residual combustion related particulates, gases, and vapours such as carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2), and more than 120 volatile organic compounds (VOCs), including carcinogens such as benzene, 1,2-butadiene, formaldehyde, naphthalene, styrene, and toluene. Formaldehyde is of particular concern in this group, given its status as a known human carcinogen and upper airway irritant. Although it is recommended that fire-fighters use SCBA during overhaul, many fire departments either do not require or do not enforce this procedure.
As a result of this increased operational risk to fire fighters, respiratory protection has now been developed to cover a wide range of firefighting scenarios utilizing both positive and negative pressure environments within the single respirator face piece. As one approach considered by fire departments to the above issues has been the use of APR, rather than SCBA during overhaul operations. For example researchers in the United States have demonstrated that air purifying respirators (APR) fitted with chemical, biological, radiological, and nuclear (CBRN) canisters may reduce occupational respiratory exposures in the fire fighting domain. Designed for Top Down Convertibility, masks such as the AV-3000 HT face piece (Figure 1) are an example of this new requirement and can be configured to operate in either APR, PAPR or positive pressure breathing apparatus (SCBA or airline supplied) modes.
The health risks entailed by fire-fighters work situation can not only lead to cancers, but other health problems such as fertility disorders, cardiovascular diseases, asthma and other allergies such as dermal and respiratory sensitization. Whilst the above respiratory protection will shield the wearer from these hazards from an inhalation perspective in a fire, it will not protect them from the long term chronic effects of contaminants adsorbed into their equipment. Long term exposure, through dermal transfer and ingestion, for example can lead to “chronic” accumulation of these carcinogenic materials into the body. If not properly addressed through correct cleaning and decontamination protocols this problem can result in long term damage to the fire-fighters health. For instance the fire-fighters’ work environment is a global problem and several types of cancer are now classed as an occupational illness for fire-fighters in Sweden, Canada, Australia and parts of the USA
Present strategies for alleviating combustion product contamination of firefighting equipment and personnel is very rudimentary and usually involves either routine washing via laundry of the equipment & clothing or direct replacement of the aforementioned equipment. Cleaning of such equipment & clothing is normally undertaken on a cyclical basis (e.g. once every 3 months) via laundry services specifically designed for such apparatus. Whilst effective, this service is a huge logistical burden in requiring large quantities of water and detergent per unit cleaned and is only undertaken sporadically over a prolonged period of time e.g. not after every incident. As a result there is an increasing likelihood of exposure to the aforementioned contaminants and therefore prolonged accumulation in the body, which can ultimately result in chronic effects being observed longer term in firefighters.
To combat this human tragedy a significant amount of research is now being undertaken across the globe to find alternative methodologies which could be used to help reduce the occupational exposure fire-fighters receive during their daily life. One alternative methodology that could conceivably be used in the future fight to reduce occupational exposure is that of dual fluid atomization technology. Dual fluid atomization systems, such as the depicted Light Decontamination System – LDS, are highly portable systems making them versatile enough to be used at the scene of any fire e.g. the firefighter could be immediately decontaminated following egress from the incident area, thereby minimizing the occupational exposure to carcinogenic materials and other related hazards.
Containing no moving parts, these dual fluid nozzle systems have the ability to deliver a wide range of decontaminants making them highly suitable for not only occupational firefighting decontamination applications but other first responder domains such as CBRN and HAZMAT incidents as well. Utilizing compressed air to atomize a liquid, not only are these systems capable of producing large dense clouds of very small droplets (typically 1-10 microns), they are also capable of reaching all non-line-of-sight surfaces. This latter facet makes them perfectly suited for decontaminating complex structures and surfaces such as the ones found in people and equipment.
Effective against both airborne and surface threats, “dual fluid” nozzles typically use 10% of the decontaminant required by existing systems to afford effective decontamination. This is again a vast improvement over the current approach to decontaminating equipment and people which involves ‘total flooding’ using large quantities of active effluent which then requires subsequent treatment and is highly inefficient in terms of cost.
Dual fluid systems, due to the large number of droplets they produce, are also capable of knocking down short range particulate hazards and the isolation of highly mobile fibers such as asbestos and radioactive materials etc, through the delivery of polymeric coatings. The system can easily be reconfigured for Toxic Industrial Chemical (TIC) and CBRN applications with minimal effort via a simple change in decontaminant. This latter feature further reduces logistical burden and offers a truly comprehensive decontamination capability in a single system. Such system integration, combining the advantages of tailor made and versatile decontaminants, with the versatility of “dual fluid” nozzle based systems will allow the first responder of the future to effect timely decontamination in any global theatre against any threat encountered. Thereby reducing the occupational hazards that first responders such as firefighters will face in the future.
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