respiratory protection against emerging hazards: nanotechnology and h1n1 influenza a virus centers...
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Respiratory Protection against Emerging Hazards: Nanotechnology and H1N1
Influenza A Virus
Centers for Disease Control and PreventionNational Institute for Occupational Safety and Health
National Personal Protective Technology LabResearch Branch
Pittsburgh, PA 15236Email: [email protected]
Phone: 412-386-4001
October 2nd, 2009
Ron Shaffer
UC PRP Symposium October 2 2009
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Overview
Respirator 101: Air purifying respirators (APR)
Emerging Hazard: Engineered Nanoparticles
Do NIOSH-certified APRs provide expected levels of filtration performance against nanoparticles?
Emerging Hazard: H1N1 Pandemic Influenza
Can disposable filtering facepiece respirators (FFRs) be decontaminated and possibly reused?
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Mine Safetyand Health
Administration(MSHA)
Department of Health and Human Services
(DHHS)
Department of Labor(DOL)
Regulation/Enforcement
OccupationalSafety and Health
Administration(OSHA)
Research, Training, andPrevention Recommendations
Centers for DiseaseControl and Prevention
(CDC)
National Institute forOccupational Safetyand Health (NIOSH)
Occupational Safety & Health Act (1970) established OSHA & NIOSH - To assure safe and healthful working conditions for all working men and women.
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42 CFR, Part 84 Air-purifying Particulate Respirator (APR) Certification
Minimum Efficiency
NaCl Test
DOP oil Test
DOP oil Test
95% N95 R95 P95
99% N99 R99 P99
99.97% N100 R100 P100
• N - not resistant to oil mist• R - resistant to oil mist• P - protective against oil mist• 95, 99, 100 - minimum filter efficiency using certification test conditions
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Filtering Facepiece Respirators (FFR)
N95 and P100 most common
Designed to form tight face seal
Entire facepiece is composed of the filtering medium
Approximate cost: $0.70 - $2.34 each
Mostly fixed-length straps
Disposable
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Elastomeric Half Mask Respirator
N95 and P100 most common
Designed to fit tightly to the face
Low maintenance - reusable facepiece and replaceable filters and cartridges
User-adjustable-length straps
Approximate cost:
Facepiece: $12 to $35
Filters: $4 to $8 each
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Example Electret Filter Media
Melt blown - Corona charged (A)
Melt blown - Highly charged (B)
Extruded - Split film fiber (C)
Melt blown - Highly charged (D)
http://www.cdc.gov/niosh/npptl/researchprojects/pdfs/NanoparticleFinalReport041006.pdf
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Conventional Single-Fiber Filtration Theory
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Current State of Respiratory Protection
Effectiveness of NIOSH-approved APRs against conventional workplace hazards has been shown
Workplace protection factor (WPF) studies
OSHA Assigned Protection Factors (APF)
Emerging hazards raise new issues:
Nanotechnology
Infectious aerosols (e.g., SARS, avian influenza, 2009 H1N1 influenza A)
Nanotechnology
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What are Nanoparticles?
Nanoparticles are particles having a diameter between 1 and 100 nm (0.001-0.1 µm)
Adapted from: Guidance for Filtration and Air-Cleaning Systems to Protect Building Environments from Airborne Chemical, Biological, or Radiological Attacks, DHHS (NIOSH) Publication No. 2003-136.
Nanoparticles
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Components of a Nanomaterial Risk Management Program
Adapted from Figure 1, Schulte et al, Occupational Risk Management of Engineered Nanoparticles, Journal of Occupational and Environmental Hygiene, 5:4, 239-249 (2008).
Hazard Determination
Process Review
Exposure Evaluation
Risk Characterization
Controls
Hierarchy of Controls
Elimination/Substitution
Engineering Controls
Administrative Controls
PPE
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Effectiveness of APR for Workers Handling Unbound Nanomaterials
Photo obtained from Health hazard evaluation report: HETA-2005-0291-3025, Methner-MM;
Birch-ME; Evans-D; Hoover-MD
Effectiveness of particulate APR is primarily a function of leakage around the face seal and penetration through the filter.
Key question: Do nanoparticles behave any differently than larger particles?
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Respirator Fit
No specific data available to determine if nanoparticle face seal leakage is different
WPF studies have validated efficacy of current methods used to fit respirators for protection against gases and vapors.
TSI PortaCount® with N95 Companion™ measures ~40 nm particles
NIOSH is conducting controlled laboratory studies using manikins to measure face seal leakage of 5 – 400 nm particles
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Filtration of Nanoparticles – New Concerns?
?
?
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Filtration Performance of a Typical NIOSH-Approved N95 Filtering Facepiece Respirator
n = 5; error bars represent standard deviationsSodium Chloride (TSI 3160); Silver (custom-built)Flow rate 85 L/min
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1 10 100 1000
Particle Size (nm)
% P
enet
rati
on
Silver Sodium chloride
Filtration performance of NIOSH-approved N95 and P100 filtering facepiece respirators against nanoparticles, [2008] S. Rengasamy, WP King, B. Eimer and R. Shaffer, Journal of Occupational and Environmental Hygiene, 5: 556-564.
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Summary : Percentage Penetration Results
Approval TypePolydisperse Aerosol Test
(PAT) (%)
Monodisperse Aerosol Test (MAT) (%)
(40 nm) (300 nm)
NIOSH N95 0.61 - 1.24 2.0 - 5.2 0.20 - 1.56
NIOSH P100 0.003 - 0.022 0.007-0.0090.0006 -
0.001
CE FFP2 0.27 - 0.50 1.45 - 2.22 0.69 - 0.84
CE FFP3 0.009 - 0.014 0.155 - 0.164 0.06 - 0.07
FDASurgicalMask 1.58 - 88.06 8.98 - 72.51 2.14 - 88.95
N/ADust Mask 1.00 - 87.02 4.31 - 81.63 0.86 - 95.05
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Correlation of Poly- and 40 nm Monodisperse Aerosol Penetrations
Shaffer, RE, Rengasamy, S., Respiratory Protection Against Nanoparticles: A Review, Journal of Nanoparticle Research (in press, available on-line).
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Where do we go from here?
PPE
Laboratory studies on efficacy of protective clothing and gloves; complete laboratory studies on respiratory protection
PPE workplace protection factor (field) studies of nanotechnology workers
Applications
Antimicrobial effects on HVAC air and respirator filters
Use of monolayer-protected gold nanoparticles in air purifying respirator end of service life indicators
http://www.cdc.gov/niosh/topics/nanotech/pdfs/NIOSH_Nanotech_Strategic_Plan.pdf
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Where to learn more
Visit the NIOSH Nanotechnology Topic Page http://www.cdc.gov/niosh/topics/nanotech/
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Summary
NIOSH has an active nanotechnology research program
For respirator filter media there is no deviation from the classical single-fiber theory for filtration of particulate as small as 4 nm in diameter
Polydisperse aerosol test provided a consistent rank-ordering of filtration performance seen with 40 nm (MPPS) monodisperse particles
It is likely that NIOSH approved APRs when used in a complete respirator program will be useful for protecting workers from nanoparticle inhalation and should provide levels of protection consistent with their OSHA assigned protection factor (APF)
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Recent Papers
Rengasamy S, Verbofsky R, King WP and Shaffer RE, Nanoparticle penetration through NIOSH-approved N95 filtering facepiece respirators. Journal of the International Society for Respiratory Protection, 24(1):49-59 (2007).
Rengasamy, S., Eimer, B, Shaffer, RE, Nanoparticle filtration performance of commercially available dust masks, Journal of the International Society for Respiratory Protection, 25(1): 27-41 (2008).
Rengasamy, S., King, WP, Eimer, B, Shaffer, RE, Filtration performance of NIOSH-approved N95 and P100 filtering facepiece respirators against 4 to 30 nanometer size nanoparticles, Journal of Occupational and Environmental Hygiene, 5(9): 556-564 (2008).
Rengasamy A, Eimer BC, Shaffer RE, Comparison of nanoparticle filtration performance of NIOSH-approved and CE-marked particulate filtering facepiece respirators. Ann Occup Hyg 53(2): 117-128 (2009).
Rengasamy, S., Miller, A., Eimer, B, Shaffer, RE, Filtration Performance of FDA-approved Surgical Masks, Journal of the International Society for Respiratory Protection, 26(1):54-70 (2009).
Shaffer, RE, Rengasamy, S., Respiratory Protection Against Nanoparticles: A Review, Journal of Nanoparticle Research (in press, available on-line).
2009 H1N1 Flu
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Background – 2006 IOM Report
>90 million N95 FFR will be needed to protect workers in the healthcare sector during a 42-day outbreak
Can disposable FFRs be reused?
Biological decontamination method must (1) remove the viral threat; (2) be harmless to the user; and (3) not compromise the integrity of the FFR.
Little data exists
http://www.nap.edu/catalog.php?record_id=11637
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Reusability of Filtering Facepiece Respirators
Task 1: Effect of decon on FFR filter performance
Task 2: Develop STP for measuring the efficacy of
FFR decon
Task 3: Survivability of virus simulant on FFR
Task 4: Reaerosolization of virus on FFR
Task 5: Assessment of decon strategies for
FFR
Task 6: Effect of decon on FFR fit
Task 7: Final Report
Task 1: Effect of decon on FFR filter performance
Task 2: Develop STP for measuring the efficacy of
FFR decon
Task 3: Survivability of virus simulant on FFR
Task 4: Reaerosolization of virus on FFR
Task 5: Assessment of decon strategies for
FFR
Task 6: Effect of decon on FFR fit
Task 7: Final Report
Goal - conduct laboratory studies to understand the efficacy of decontamination and to assess the impact of decontamination on FFR performance
Note: Tasks 3 and 4 (not shown) are related to other aspects of the projectNote: This presentation only includes data from the NIOSH funded project. Data from our TSWG-funded collaboration with AFRL, FDA, University of Florida, and University of Nebraska is not included.
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Task 1. Effect of Decontamination on Filtration
Experimental Design
1 N95 and 1 P100 FFR model
Automated systems: autoclave, VHP, EtO
Chemical: IPA, Bleach, LHP, Soap & Water
Physical: UV, microwave, heat
Controls: water, no decon
Findings
Autoclave, 160º C heat, 70% IPA, and soap & water caused significant filter degradation
Bleach, EtO, and a microwave degraded filter performance, but particle penetration levels were still less than the NIOSH certification criteria.
HP (vaporized and liquid forms) and UV radiation caused no significant changeViscusi DJ, King WP, Shaffer RE. Effect of Decontamination on the Filtration Efficiency of Two Filtering Facepiece Respirator Models. Journal of the International Society for Respiratory Protection, (2007) 24: 93-107.
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Effect of Decontamination on Physical Appearance, Odor, and Laboratory Performance
Findings
Effects were model specific. FFRs tested have differences in their design (e.g., # of layers, face seal enhancements) and materials of construction (e.g., hydrophobicity)
Inner face seal liner (P100) and material near metal nose clip (Surgical N95) on two FFR models melted in microwave
All other combinations had expected levels of laboratory performance (filtration, air flow resistance)
Bleach has noticeable odor - even after drying 22 hours - and low levels of chlorine gas were found after rehydration
Experimental Design
3 N95, 3 Surgical N95, 3 P100 FFRs
Bleach, UV, VHP, EtO, and Microwave
Viscusi DJ, Bergman, M.S., Eimer, B.C., and Shaffer RE. Evaluation of Five Decontamination Methods for Filtering Facepiece Respirators. Annals of Occupational Hygiene (in press).
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N95 FFR average initial sodium chloride filter aerosol penetration versus temperature
Five SN95-D FFRs melted: one at 100C, two at 110C, and two at 120C
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Modes of Contamination
Respirator User
Infected Person
Sneezing
Coughing
Breathing
Talking
Droplets (~0.5 - 10+ µm)
Droplet nuclei (~0.3 - <5 µm)
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Microphotographs of the FFR Loaded with Aerosol to 1E+05 pfu/cm2(Left: Outer Layer and Right: Media Layer)
10 µmMicrophotographs of the FFR Loaded with Liquid Droplets
(Left: Outer Layer and Right: Media Layer)
Aaron W. Richardson, Shannon D. Harpest, and Kent C. Hofacre, Reaerosolization of Viruses from NIOSH-certified Filtering Facepiece Respirators, Battelle Columbus Operations, Final Report to NIOSH on Contract No. 200-2000-08018
Visual Differences in Aerosol and Pipette Loading Methods
10 µm
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Bio-Aerosol Respirator Test System (BARTS)
1. Air supply 2. Regulator 3. HEPA filter 4. Nebulizer air 5. Nebulizer 6. Dilution air 7. Chamber
8. Circulation fan 9. Exhaust port 10. Test holders11. Flow meter12. Vacuum pump13. Timer14. Power
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2
25
6
3
7
8
12
13
14
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3
14
11
11
3
93
10
10
Schematic
Photo
Fisher, E., Rengasamy, S., Viscusi, D., Vo, E., and Shaffer, R., Development of a Test System to Apply Virus-Containing Particles to Filtering Facepiece Respirators for the Evaluation of Decontamination Procedures, Applied and Environmental Microbiology, 75(6): 1500-1507 (2009)
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BARTS ValidationCombined APS & SMPS Data
Size distribution of MS2 aerosol challenge highly dependent upon concentration of protective factor
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BARTS Validation
Some virus-containing droplet nuclei penetrate through the filter layers – distribution through the FFR is highly dependent upon concentration of protective factor
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Example Applications of BARTS
Bleach Microwave Generated Steam (MGS)
Decontamination efficacy increases as a function of dose and time
Increased organic load (protection factor) in the MS2 viral aerosol challenge reduced decontamination efficacy for bleach, but not MGS
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Droplet Phase Aerosol Respirator Test System (DPARTS)
Schematic
Vo, E., Rengasamy, S., and Shaffer, R., Development of a Test System to Evaluate Decontamination Procedures for Viral Droplets on Respirators Applied and Environmental Microbiology, (in press).
Challenge Aerosol
T
C R
B
L
6B
APS1
3
5
4
7 2
2
6
8
1. compressed air supply 2. HEPA filter3. air flow regulator 4. nebulizer air inlet 5. nebulizer
6. FFR 6B. FFR sample coupons on the respirator7. exhaust port with HEPA filter; 8. aerodynamic particle sizer
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Example Applications of DPARTS
Bleach UV
Decontamination efficacy increases as a function of dose
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Summary
Some biological decontamination methods caused significant changes in physical appearance and/or degradation in laboratory performance. Some of these effects were model specific.
BARTS and DPARTS produce reproducible MS2 phage aerosol challenges for FFR decontamination efficacy studies
UV, microwave generated steam, and moist heat appear to be promising, but additional research is necessary:
Can the low-temperature biological decontamination methods reduce viable MS2 particles to acceptable levels (with or without a cleaning step)?
Does decontamination change FFR fit?
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Respiratory Protection Research Needs
Aerosol/Filtration Studies
Antimicrobial
Respirator Fit Research
Facial anthropometrics
Fit Testing
Novel respirator designs
Influenza Pandemic
Assess strategies to prevent FFR shortage
Performance (laboratory & field)
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Acknowledgements
NIOSH NTRC for funding a pilot study on nanoparticle filtration
CDC for initial funding on the development of BARTS and the FFR reuse study
DoD (TSWG) for continued support of the FFR reuse study (multiple decontaminations, fit testing study). Air Force Research Laboratory for providing the H1N1 decontamination data (not presented).
Respiratory Protection against Nanoparticle Team: Samy Rengasamy (PI), Ben Eimer, Bill King
FFR Reuse Team: Dennis Viscusi, Evanly Vo, Samy Rengasamy, Ed Fisher, Debbie Novak, Bill King, Mike Bergman
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Quality Partnerships Enhance Worker Safety & Health
Thank you
Visit Us at: http://www.cdc.gov/niosh/npptl/Disclaimer:
The findings and conclusions in this presentation have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.
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Extra Slides
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Nanoparticles - Health Concerns
Airborne nanomaterials can be inhaled and deposited in the respiratory tract
Nanomaterials can enter the blood stream and translocate to other organs
Mass doses of insoluble nanoparticles are more potent than larger particles of similar composition in causing pulmonary inflammation and lung tumors in laboratory animals
Changes in the chemical composition, structure of the molecules, or surface properties can influence potential toxicity http://www.cdc.gov/niosh/topics/nanotech/
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Primary Decontamination MethodsTSWG Funded Collaboration
Microwave Generated Steam2 min on ‘High’ power (2 pipette-tip boxes each with 50 ml tap water)
Figure 12.2: Treatment of FFRs with 254 nm UV lightUV-C Light254 nm at 2.0 mW/cm2 for 15 min each side
Moist HeatIncubator (60°C, 80% RH) for 30 min
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Quick Comparison of the Systems BARTS
Droplet Nuclei
Coupons
Vacuum pulls challenge into media of the coupon
Simulate air circulating particles
DPARTS
Droplet
Full FFR
Direct spray onto the surface of the respirator
Simulates direct particle deposition (sneeze or cough)
Fisher E., Rengasamy S., Viscusi D., Vo E., and R. Shaffer. 2009. Development of a Test System To Apply Virus-Containing Particles to Filtering Facepiece Respirators for the Evaluation of Decontamination Procedures. APPLIED AND ENVIRONMENTAL MICROBIOLOGY 75:1500–1507.
Vo E., Rengasamy S., and R. Shaffer. 2009. Development of a Test System to Evaluate Decontamination Procedures for Viral Droplets on Respirator Surfaces. APPLIED AND ENVIRONMENTAL MICROBIOLOGY (in press)
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Aerosol Media used in BARTS Characterization and Validation
ATCC medium 271
Growth medium for E. coli (used to propagate and enumerate MS2)
Protective factor (organic challenge) in decontamination testing
High Protective Factor (HPF)
Low Protective Factor (LPF)
Follows the parameters set forth in ASTM E 1053 (Efficacy of Virucidal Agents Intended for Inanimate Environmental Surfaces)
ATCC 271 Water LPF (1%) * HPF (100%) * ASTM E 1053 *
Tryptone - .10 10.0 7.6
Yeast extract - .01 1.0
Sodium chloride - .08 8.0 8.5
Glucose - .01 1.0
Calcium chloride - .002 0.22
Thiamine - .0001 .01 * Constituents (g/L)