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Specification of appropriate personal protective equipment for respiratory protection against influenza is somewhat controversial. In a clinical environment, N95 filtering facepiece respirators (FFRs) are often recommended for respiratory protection against infectious aerosols. This study evaluates the ability of N95 FFRs to capture viable H1N1 influenza aerosols. METHODs. Five N95 FFR models were challenged with aerosolized viable H1N1 influenza and inert polystyrene latex particles at continuous flow rates of 85 and 170 liters per minute. Virus was assayed using Madin-Darby canine kidney cells to determine the median tissue culture infective dose (TCID50). Aerosols were generated using a Collison nebulizer containing H1N1 influenza virus at 1 x 10(8) TCID50/mL. To determine filtration efficiency, viable sampling was performed upstream and downstream of the FFR. RESULTS. N95 FFRs filtered 0.8-microns particles of both H1N1 influenza and inert origins with more than 95% efficiency. With the exception of 1 model, no statistically significant difference in filtration performance was observed between influenza and inert particles of similar size. Although statistically significant differences were observed for 2 models when comparing the 2 flow rates, the differences have no significance to protection. CONCLUSIONS. This study empirically demonstrates that a National Institute for Occupational Safety and Health-approved N95 FFR captures viable H1N1 influenza aerosols as well as or better than its N95 rating, suggesting that a properly fitted FFR reduces inhalation exposure to airborne influenza virus. This study also provides evidence that filtration efficiency is based primarily on particle size rather than the nature of the particle's origin., Published in Infection Control and Hospital Epidemiology, v34 n5 p494-499, May 2013.

Improved respirator test headforms are needed to measure the fit of N95 filtering facepiece respirators (FFRs) for protection studies against viable airborne particles. The objective of this study was to develop and evaluate a medium-size Static (i.e., non-moving, non-speaking) Advanced headform (StAH) for fit testing N95 FFRs. The StAH was developed based on the anthropometric dimensions of a digital headform reported by the National Institute for Occupational Safety and Health and has a silicone polymer skin with defined local tissue thicknesses. Quantitative fit tests were performed on seven N95 FFR models of various sizes and designs. Donnings were performed with and without a pre-test seal checking method. For each method, four replicate FFR samples were tested of each of the seven models with two donnings per replicate, resulting in a total of 56 tests per donning method. Each fit test was comprised of three one-minute exercises: Normal Breathing (NB, 11.2 liters per minute (lpm)), Deep Breathing (DB, 20.4 lpm), then NB again. A fit factor (FF) for each exercise and an overall test FF were obtained. Analysis of variance methods were used to identify statistical differences among FFs (analyzed as logarithms) for different FFR models, exercises, and donning methods. For each FFR model and for each donning method, the NB and DB FF data were not significantly different (p 0.05). Significant differences were seen in the overall exercise FF data for the two donning methods among all FFR models (pooled data) and in the overall exercise FF data for the two donning methods within certain models. A seal-checking method improved the frequency of obtaining overall exercise FFs 100. The FFR models, which are expected to achieve FFs 100 on human subjects, achieved FFs 100 on the StAH. Further research is needed to evaluate the correlation of FFR fit on the StAH to FFR fit on people., Published in Journal of Occupational and Environmental Hygiene, 11:2, 117-125, 2014.

Decontamination and reuse of filtering facepiece respirators (FFRs) has been proposed to mitigate an anticipated shortage of FFRs caused by pandemic influenza. A wealth of research has been reported on this topic, but a data gap exists in the area of cleaning FFRs. This study evaluates the cleaning of three surgical N95 FFRs by three commercial wipe products as an initial exploration of this area. FFRs were contaminated with either Staphylococcus aureus or mucin using aerosol methods, then cleaned with one of three wipe products --two of which contain antimicrobial agents (hypochlorite and benzalkonium chloride (BAC)). Prior to extraction and quantification of the contaminants, the FFRs were deconstructed and separated into the principal components (nose pad, fabrics, and perforated edge strip, if present), allowing the cleaning efficiency for each piece to be evaluated separately. The antimicrobial-free wipe achieved 1-log reduction in viable S. aureus on the FFR fabrics from all three FFR models. Removal was less effective on FFR nose pads and perforated edges. The antimicrobial wipes achieved 35-log reduction in viable S. aureus on most samples, presumably aided by disinfectant properties. Lower reductions were observed on nose pads; higher reductions were observed on materials with rough textures, presumably due to accumulation of the antimicrobial agent in these areas. Mucin removal efficiency was 1 log on all FFRs. Evaluation of particle penetration following cleaning yielded mean values 5%. However, the wipe containing BAC enabled significantly higher penetration than the other wipe products. The significance of these data to the concept of decontamination and reuse of FFRs will remain open to consideration until actual contamination of these devices during use has been measured. This study will both lead to and inform future research aimed at developing better FFRs., The original document contains color images. Published in American Journal of Infection Control, 2013.

Viral aerosols collected on a filter medium can reaerosolize and the filter can serve as a fomite. This study evaluated the inactivation efficiency (IE) achieved by filtration coupled with microwave irradiation. To test in-flight microwave decontamination, microwave irradiation was applied to coupons cut from a ventilation filter and supported on a SiC disk during three cycles of selected irradiation times (1, 2.5, 5, and 10 min) per 10 min of delivery of microwave power at levels ranging from 125 to 375 W. The survival fraction (SF) on the substrate and the IE through the entire system were investigated to determine the efficacy of this approach. SF decreased and IE increased as microwave power level increased or the application time was extended. Both measures changed sharply above a threshold temperature of 90 ?C reaching -2 logs at 116 and 2 logs at 109 ?C, respectively. Operating on a SiC disk (to facilitate microwave absorption at 375 W for 10 min/cycle, log SF and IE were -2.59 and 3.62, respectively, when the. On a quartz frit instead of the SiC disk, the same power regime caused log IEs of 0.8, 1.0, and 1.3 at relative humidities of 30%, 60% and 90%, respectively. The results demonstrate that microwave-assisted filtration systems can be used as an effective means for inactivating viruses.

Although respirators and filters are designed to prevent the spread of pathogenic aerosols, a stockpile shortage is anticipated during the next flu pandemic. Contact transfer and reaerosolization of collected microbes from used respirators are also a concern. An option to address these potential problems is ultraviolet (UV) irradiation, which inactivates microbes by dimerizing thymine in nucleic acids. The objective of this study was to determine the effects of transmission mode and environmental conditions on decontamination efficiency by UV. In this study, filters were contaminated by different transmission pathways (droplet and aerosol) using three spraying media (deionized water (DI), beef extract (BE), and artificial saliva (AS)) under different humidity levels (30% (LRH), 60% (MRH), and 90% (HRH)). UV irradiation at constant intensity was applied for two time intervals at each relative humidity condition. The highest inactivation efficiency (IE), around 5.8 logs, was seen for DI aerosols containing MS2 on filters at LRH after applying an UV intensity of 1.0 mW/cm2 for 30 min. IE of droplets containing MS2 was lower than that of aerosols containing MS2. Absorption of UV by high water content and shielding of viruses near the center of the aggregate are considered responsible for this trend. Across the different media, IEs in AS and in BE were much lower than in DI for both aerosol and droplet transmission, indicating that solids present in AS and BE exhibited a protective effect. For particles sprayed in a protective medium, RH is not a significant parameter., Published in Applied and Environmental Microbiology, v78 n16 p5781-5787 Aug 2012.

A major concern among healthcare experts is a projected shortage of N95 filtering facepiece respirators (FFRs) during an influenza pandemic. One option for mitigating an FFR shortage is to decontaminate and reuse the devices. Many parameters must be evaluated to verify the effectiveness of this strategy: biocidal efficacy, filtration performance, pressure drop, fit, and residual toxicity. The focus of this research effort was to evaluate the ability of microwave/steam energy, low-temperature moist heat, and ultraviolet germicidal irradiation at 254 nm to decontaminate H1N1 influenza virus loaded onto FFRs as either aerosols or droplets. Our data indicate that all three decontamination technologies provide 4-log reduction of viable H1N1 virus --in 93% of our experiments, the virus was removed to levels below the method detection limit. These data are encouraging and may contribute to the evolution of effective strategies for decontamination and reuse of FFRs., Prepared in cooperation with University of Florida, Gainesville, FL. Pub. in American Journal of Infection Control, v39 nn1, p.e1-e9, Feb 2011.

Efforts to measure the clinical significance of an antimicrobial resin incorporated in air filtration media marketed for use in personal respirators identified the need for a novel system to perform comparative animal inhalation studies using infective bioaerosols. An aerosol delivery system based on the Collison nebulizer and a 12-port, commercial apparatus for respiratory exposure of rodents was designed and engineered to deliver, at selectable concentrations, a respiratory challenge of bioaerosols through a filter exclusively to the noses of mice. Pathogenic bioaerosols can be passed in separate experiments through treated and untreated control filters to deliver a consistent challenge to a murine model of human respiration via a nose-only exposure, as a detector for antimicrobial effect. This system was validated and found to be capable of providing a sufficiently constant and controllable stream of viable bioaerosol for use in animal exposure trials., Published in Journal of Applied Microbiology, v113, 757-766, 2012.

Methyl Salicylate (MeS) has been widely used as a surrogate for the chemical agents GD and HD in tests such as vapor penetration because all three exhibit similar volatility. The chemistry of the same three chemicals is grossly dissimilar, and different surrogates --e.g., diisopropyl fluorophosphate for GD in challenges by a nucleophilic neutralizing agent, because both share the R-O-P-F functionality --are generally used for tests of reactivity with potential neutralizing agents. However, the phenolic -OH of MeS suggests oxidizability, which raised the possibility that MeS might function as a surrogate for examining the efficiency of coverage and distribution of a sprayed oxidizing agent as a neutralizing treatment., PDF updated 26 Feb 2013.

To provide a method of detecting clinical response as a complement to a bioaerosol delivery system (CATS) designed to measure infective penetration of respiratory protective devices, an animal model system was developed for measuring the infectivity of aerosol challenges delivered to mice. The CATS was used to deliver graduated doses of influenza A/PR/8/34 (H1N1) by inhalation to 25-g female CD-1 mice, from which a median infective dose (MID50) of less than 40 TCID50 was inferred from weight loss, and a lower-limit value of 12 TCID50 was calculated from cytopathic effect and qRT-PCR data. The information derived from this study can be used to further the development of mouse models for evaluating aerosol delivery of pharmaceuticals and technologies for infectious disease control, and to create and validate computational models for aerosol delivery., Published in Journal of Applied Microbiology v113 p767-778, 2012.

Single-use filtering facepiece respirators (FFRs) are effective precautions against airborne pathogenic microorganisms; however, during pandemics the demand for FFRs may far exceed availability. Reuse of FFRs following decontamination has been suggested but few studies to date have addressed the feasibility. Concerns regarding biocidal efficacy, filter performance post decontamination and cost of decontamination may affect the adoption of reuse measures. This study examined the effectiveness of three energetic decontamination methods (ultraviolet germicidal irradiation, microwave-generated steam and moist heat) on two NIOSH certified N95 FFRs contaminated with H5N1. An aerosol settling chamber was used to apply virus-laden droplets to FFRs in a method designed to simulate respiratory droplet deposition of viruses onto surfaces. Results differed based on the method used for detection of the virus. When the FFRs were examined post decontamination by virus culture, all three decontamination methods worked equally well and reduced virus load by 4 log TCID50. Analysis of the treated FFRs using a quantitative molecular amplification assay (qRT-PCR) indicated that the UVGI decontamination method provided lower levels of detectable genome copies than the other two methods. Filter performance was evaluated before and after decontamination using a 1% NaCl aerosol. All FFRs displayed penetration below 5% at the 300- nm particle size. No reduction in filtration performance was found in FFRs that had been exposed to virus and subsequently decontaminated. These findings indicate that, when properly implemented, decontamination methods are effective for FFRs and do not affect their filtering function; however, other factors may affect the decision to re-use FFRs., Published in The Annals of Occupational Hygiene, 2011.

By analogy to the accepted mechanism for disinfection by iodine in water, a mechanism was earlier proposed to rationalize in-vitro disinfection of bioaerosols after passage through air filter media coated with poly[styrene-4-(trimethylammonium)methyl triiodide] (PSTI) that invoked near-collision transfer of I2 from PSTI onto the negatively charged surface of passing particles. This report describes progress toward two experiments designed to test and refine that model and to evaluate the increment to respiratory protection available by adding PSTI to inert mechanical air filter media. The controlled aerosol test system (CATS) was designed and built to deliver a constant (+/- 10%) challenge of aerosolized respiratory pathogens through samples of air filter media to groups of 5 mice. By varying the challenge concentration and comparing rates of infection in groups behind mechanically equivalent control and PSTI-containing media we expect to measure the effective decrease in penetrating infectivity. The second experiment was accomplished in 20-L bags assembled from commercial food wrapping material, which were filled with a bioaerosol of MS2 coli phage that had been passed through an inert or PSTI-containing air filter medium. After 15 or 30 minutes' incubation the contents of the bag were drawn through an impinger containing dilute thiosulfate solution and plated to determine viable counts. Data noise in the control experiment prevented drawing a firm conclusion but loss of viability in the aerosol phase appeared faster in the treated group at high humidity, suggesting that water is necessary to the antimicrobial action and that PSTI might be more effective in collective than individual protection applications.

A major concern among healthcare experts is a shortage of supplies during a pandemic. An item of particular interest is the N95 filtering facepiece respirator (FFR), which is responsible for protecting individuals from infectious aerosols. Most experts agree there will be a shortage of N95 FFRs if a severe pandemic occurs and one option for mitigating an FFR shortage is to decontaminate and reuse the devices. Many parameters must be studied to verify the effectiveness of this strategy: biocidal efficacy of the decontamination treatment, filtration performance, pressure drop, fit, and toxicity to the end user post treatment. The focus of this research effort was to measure chemical off-gassing of six types of FFRs following decontamination. Our data indicate that for disinfectants, such as hydrogen peroxide and bleach, the amount of residual decontaminants is below the Permissible Exposure Limit (PEL). Toxic by-products were also evaluated, and they were detected for ethylene oxide treatment of FFR rubber straps. These data are encouraging and may contribute to the evolution of effective strategies for decontamination and reuse of FFRs., Submitted to the Journal of Material Science, Springer edition.

High Efficiency Particulate Air (HEPA) filters are the primary technology used for particulate removal in individual and collective protection applications. HEPA filters are commonly thought to be impenetrable, but in fact they are only 99.97% efficient at collecting the most-penetrating particle (approx. 0.3 micrometer). While this is an impressive collection efficiency, HEPA filters may not provide adequate protection for all threats: viruses are submicron in size and have small minimum infections doses (MID50). Thus, an appropriate viral challenge may yield penetration that will lead to infection of personnel. However, the overall particle size (agglomerated viruses and/or viruses attached to inert carriers) will determine the capture efficiency of the HEPA filter. Aerosolized viruses are commonly thought to exist as agglomerates, which would increase the particle size and consequently increase their capture efficiency. However, many of the threat agent viruses can be highly agglomerated and still exist as submicron particles. We have demonstrated that MS2 coli phage aerosols can penetrate Carbon HEPA Aerosol Canisters (CHAC). At a face velocity of 2 cm/sec, a nebulized challenge of approx. 105 viable plaque forming units (PFU) per liter of air results in penetration of approx. 1 - 2 viable PFU per liter of air. We are currently investigating the particle size distribution of the MS2 coli phage aerosol to determine if the challenge is tactically relevant. Preliminary results indicate that 200-300-nanometer particles account for approx. 7.5% of the total number of particles. Our aim is to characterize multiple aerosol conditions and measure the effects on viable penetration. This study will expand our knowledge of the tactical threat posed by viral aerosols to HEPA filter systems., Submitted for publication in Applied Research Associates, Inc. technical journal.

An AGI-30 impinger containing particles (MS2 bacteriophage or 30-nm polystyrene latex (PSL)) of known concentration was operated with sterile air. Reaerosolized particles as a function of sampling flow rate and impinge collection liquid concentration were characterized using a Scanning Mobility Particle Sizer. Reaerosolization from the impinge was also compared to that from a BioSampler. Results show that the reaerosolization increases as flow rate increases. While the increased particle concentration in the impinge collection liquid leads to an increase in the reaerosolization of PSL particles, it does not necessarily lead to an increase in the reaerosolization of virus particles. Reaerosolization of virus particles begins to decrease as the particle concentration in the impinge collection liquid rises above 106 PFU/mL. This phenomenon likely results from the aggregation of viral particles at high concentrations. Compared with micron-sized particles, nanosized virus particles are easier to aerosolize due to reduced inertia. Reaerosolization from the BioSampler is demonstrated to be significantly less than that from the impinge. Reaerosolization from impingement sampling methods is a mode of loss in airborne virus sampling, although it is not as significant a limitation as the; primary particle size of the aerosol. Utilizing a BioSampler coupled with shorter sampling periods to prevent high accumulative concentrations can minimize the impact of reaerosolization. This study confirms reaerosolization of virus particles to be a mode of loss in impingement sampling and identified methods to minimize the loss., The original document contains color images. All DTIC reproductions will be in black and white. Work unit no. QL102008.

The filter's physical (PRE) and viable removal efficiencies (VRE) were investigated with challenges of MS2 bacteriophage aerosols, and the infectivity of MS2 collected on the filter was analyzed. To test a proposed inactivation mechanism, media containing thiosulfate or bovine serum albumin (BSA) were put in impingers to quench and consume I2 released from the filter. In direct plating experiments, treated filters presented significantly higher VREs than did untreated filters; however, collection in excel BSA decreased VRE by half and in thiosulfate the apparent VRE decreased drastically. No significant difference in infectivity of retained viruses on treated and untreated filters was observed at the same environmental condition. Evidence presented herein for competition by dissolved I2. It also requires that dissociation of iodine from the filter and capture of iodine by MS2 aerosols as they pass through the filter be factored in the design of the assessment methodology. The filter's strong retention capability minimizes reaerosolization but also makes it difficult to discriminate the antimicrobial effect at the surface., The original document contains color images. All DTIC reproductions will be in black and white. Submitted for Publication in the Journal of Applied Microbiology, April 2009.

The advent -- 60 years after the concept was first proposed -- of practical self-decontaminating materials coincides with international efforts to prepare for global viral epidemics to highlight a need for a method to rapidly and reproducibly contaminate surfaces with pathogenic bioaerosol particles and representative surrogates. Slow rotation of a single collection stage in a cascade impactor downstream of a Collison nebulizer is demonstrated to deposit by impaction a rotationally symmetric distribution of particles containing a single spore of Bacillus globigii or vegetative Staphylococcus aureus bacterium. The coefficient of variation observed for deposition on glass plates was approx. 14%, significantly less than the acceptance criterion of 20%, and deposition time is approx. 20 min. Particle size distribution can be manipulated -- by changing the nozzle in the Collison, by changing the concentration of inert organics added to the atomization mixture, or both -- suggesting a possibility of selectively depositing larger particles containing multiple organisms.

Contamination of infrastructure and equipment with biowarfare agents has led to the development of antimicrobial surfaces/coatings that are designed to "self-sterilize". Surfaces will likely be contaminated via an aerosol exposure and thus antimicrobial efficacy measurements should also be performed using biological aerosols. Standard tests that use microbial agents suspended in aqueous buffers may provide misleading results that overestimate the performance of the surface. A settling chamber is the most common instrument for applying biological aerosols to surfaces. However, settling chambers have some drawbacks that make them undesirable for all applications (i.e., slow loading times, large footprint, variable loading, etc.). We developed a Dry Aerosol Deposition Device (DADD) that uses impaction rather than settling for loading surfaces with biological aerosols. The use of impaction allows for rapid and highly reproducible loading of microorganisms onto surfaces. We demonstrated that the DADD can deliver both Bacillus atrophaeus spores and Staphylococcus aureus vegetative cells to glass coupons at concentrations exceeding 1x10,000 CFU/sq cm. The coefficient of variation (CV) for sample-to-sample loading within an experiment was 13.6% for spores and 6.1% for S. aureus cells. The DADD is also a relatively simple and inexpensive device that can easily be contained within a 4' biological safety cabinet., The original document contains color images. Submitted for publication in the Journal of Microbial Methods.

A slide show describing progress to 5 Dec 2007 toward reproducibly contaminating sensitive equipment items and measuring the efficacy of different surface treatments as countermeasures to bioaerosol contamination. A small contamination chamber was fabricated and shown to achieve good reproducibility delivering Bacillus atrophaeus spores (13.6% coefficient of variation). Successful delivery (CV = 7.2%) of Staphylococcus aureus at 10e4/sq cm was also achieved in the small-scale chamber by aerosolization in a medium containing 1% raffinose. Batch contamination of larger items (hand-held electronic devices) was achieved by placing them inside a bioaerosol test chamber that is regularly used to deliver aerosols for filter challenge studies and arresting airflow overnight after steady-state bioaerosol concentrations were established. Loadings larger than 10e4/sq cm were again achieved. A direct extraction procedure with mechanical agitation was used to recover B. atrophaeus spores from glass slides used as controls, and two methods, HEPA vacuum and rayon gauze wipes were used to recover spores from treated and untreated calculators. HEPA recovery was both less convenient and less efficient but CVs for both methods were less than 4%., The original document contains color images.

High Efficiency Particulate Air (HEPA) filters are the primary technology used for particulate removal in many individual and collective protection applications. HEPA filters are commonly thought to be impenetrable to particulate matter, but in fact they are only 99.97% efficient at collecting the most penetrating particle (~ 0.2 micrometer). While this is an impressive collection efficiency, HEPA filters may be vulnerable to certain types of threats: Viruses are submicron in size and most have very small minimum infections doses (MID). Therefore, an appropriate viral challenge will yield penetration that exceeds the MID, for many of the threat agent viruses. Nonetheless, the overall particle size (agglomerated viruses and/or viruses attached to inert carriers) will determine the capture efficiency by HEPA filters. Aerosolized viruses are commonly thought to exist as agglomerates, which would increase the particle size and render them more prone to capture. However many of the threat agent viruses can be highly agglomerated and still exist as submicron particles. Furthermore the stability of aggregates is not well understood, and they may break apart during filtration. We have demonstrated in our laboratory that biological aerosols of MS2 coli phage, a common viral simulant, can penetrate both Carbon HEPA Aerosol Canisters (CHAC) and flat sheet HEPA material. The penetration is linear over time, thus viral penetration exceeding the MID is expected to occur in minutes following a viral challenge. We are currently investigating the particle size of the MS2 coli phage aerosol and our aim is to shift the particle size to see what effect it has on penetration. Furthermore, we are evaluating the penetration characteristics of a mammalian virus, which may better represent the threat agent viruses., The original document contains color images. Pres. at Proceedings for the ASM Biodefesne and Emerging Disease Research Meeting (5th) held in Washington, DC on 27 Feb to 2 Mar 2007.

U.S. Environmental Protection Agency (EPA) Emission Measurement Center (EMC), in conjunction with EPA Regions VI and VIII, the State of Utah and the US Department of Defense, have conducted a series of long-term pilot and field tests to determine the accuracy and reliability of a visible opacity monitoring system consisting of a conventional digital camera and a separate computer software application for plume opacity determination. This technology, known as the Digital Opacity Compliance System (DOCS), has been successfully demonstrated at EPA-sponsored Method-9 "smoke schools" as well as at a number of government and commercially operated industrial facilities. Results from the current DOCS regulatory pilot study demonstrate that, under regulatory enforcement conditions, the average difference in opacity measurement between the DOCS technology and EPA Reference between the DOCS technology and EPA Reference Method 9 (Method 9) is 1.12%. This opacity difference, which was computed from the evaluation of 241 regulated air sources, was found to be statistically significant at the 99% confidence level. In evaluating only those sources for which a nonzero visible opacity level was recorded, the average difference in opacity measurement between the DOCS technology and EPA Reference Method 9 (Method 9) was 1.20%. However, in this case, the opacity difference was found to be not significant at the 99% confidence level, a finding that suggests that the two opacity measurement methods are statistically equivalent when measuring nonzero visible opacity emissions. Given the costs and technical limitations associated with use of Method 9, there is a recognized need to develop accurate, reproducible, and scientifically defensible alternatives to the use of human observers. The use of digital imaging/processing brings current technology to bear on this important regulatory issue., Published in the Jnl. of the Air and Waste Management Association v56, p1260-1266, 2006.

The use of activated carbon fabrics (ACFs) that are desorbed electrothermally, also known as the Joule effect, is explored as a potential method to create a regenerating chemical warfare agent (CWA) filter. Electrical resistance vs. temperature measurements are presented for kynol-based ACF and compared with results for ACFs produced from other substrates. Adsorption and desorption results for dimethyl-methylphoshonate (DMMP) demonstrate that organophosphate compounds can be effectively desorbed from ACF. Chloroethane and propane are used to simulate the behavior of low-molecular-weight CWAs. Results for these more weakly adsorbed simulants indicate that a system that could indefinitely reject HCN without impregnants may be feasible. Planned efforts to advance this technology by both experimentation and modeling are discussed., The original document contains color images.

The use of activated carbon fabrics (ACFs) that are desorbed electrothermally, also known as the Joule effect, is explored as a potential method to create a regenerating chemical warfare agent (CWA) filter. Electrical resistance vs. temperature measurements are presented for Kynol(TM)-based ACF and compared with results for ACFs produced from toehr substrates. Adsorption and desorption results for dimethyl methylphosphonate (DMMP) demonstrate that organophosphate compounds can be effectively desorbed from ACF. Chloroethane and propane are used to simulate the behavior of low-molecular-weight CWAs. Results for these more weakly adsorbed simulants indicate that a system that could indefinitely reject HCN without impregnants may be feasible. Planned efforts to advance this technology by both experimentation and modeling are discussed., The original document contains color images.

4th Bi-Annual DOD JOCOTAS Meeting with Rigid & Soft Wall Shelter Industry & Outdoor Exhibition, 2-4 May 2005, Port Hueneme, CA. Document contains briefing charts. The original document contains color images.