Reusability of Facemasks During an Influenza Pandemic Facing the Flu (2006) / Chapter Skim
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2 Characteristics of Respirators and Medical Masks
2 Characteristics of Respirators and Medical Masks
Pages 22-41
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From page 22... ...
, in its respiratory protection standard Code of Federal Regulations Title 29, Part 1910.134, requires that businesses provide respirators to reduce employee exposure to respiratory hazards of all types, including dusts, fumes, and vapors; this standard extends to workers who will be in environments where exposure to tuberculosis is likely (OSHA, 1998)
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. The performance of a respirator or medical mask depends on the efficiency of the filter (how well it is able to collect airborne particles)
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For filtration and trapping of aqueous particles (as in respirators and medical masks) , polypropylene fiber surfaces require modifica tion to render them more hydrophilic (water attracting)
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This addition enhanced the efficiency many times over the basic wool material. However, the efficiency of resin electrostatic filters is degraded when they are exposed to airborne oil mists and other materials that shield the electrostatic charge.
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From page 26... ...
. It requires the employer to develop and implement a written respiratory protection program with required worksite-specific procedures and elements for respirator use that include · procedures for selecting respirators; · fit-testing methods for tight-fitting respirators; · medical evaluation of employees required to use respirators; · procedures and schedules for cleaning, disinfecting, storing, inspecting, repairing, discarding, and otherwise maintaining respirators; · procedures to ensure adequate air quality, quantity, and flow of breathing air for atmosphere-supplying respirators; · procedures for proper use of respirators in routine and reasonably foreseeable emergency situations; · training of employees in the proper use and maintenance of respirators, including putting on and removing them and any limitations on their use; and · procedures for regularly evaluating the effectiveness of the program.
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From page 27... ...
. Air-purifying respirators include those that employ filters to remove airborne particulate matter (such as N95 filtering facepiece respirators)
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. N95 filtering facepiece respirators and half-mask elastomeric respirators cover the wearer's nose and mouth, whereas full facemasks also protect the eyes.
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From page 29... ...
N95 Respirators Most filtering facepiece respirators are manufactured only in the N95 configuration. For healthcare settings, the term "N95 respirator" has become synonymous with N95 filtering facepiece respirators (as opposed to those that have reusable facepieces but employ N95 filters)
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From page 30... ...
It is hypothesized that most of the contaminants enter through faceseal leakage rather than filter penetration. Published studies conducted in laboratory and workplace environments have examined the total inward leakage of respirators worn by subjects who have been properly fit-tested and trained with a fully functional N95 filtering facepiece.
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From page 31... ...
Some N95 filtering facepiece respirators have exhalation valves placed near the mouth of the wearer. Exhalation valves bypass the filter media and significantly reduce the effort required to exhale and also increase the wearer's comfort as there is less heat and moisture buildup.
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From page 32... ...
aureus filtration test, per of about 0.3 µm ASTM standard (PFE) Airflow rate 85 L/min 28 L/min Test aerosol Charge neutralized test Unneutralized test aerosol aerosol Preconditioning Preconditioning at 85% No preconditioning relative humidity and 38°C for 24 hrs Faceseal fit Designed to fit tightly to face Not designed to fit to face Annual fit-test required Fit check Required with each use Not designed for fit check requirements Available sizes Some models available in Only one facepiece size generally three sizes available.
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From page 33... ...
Surgical N95 · Blocks particles < 100 µm from being inhaled · Reduces the transfer of respiratory droplets to others · Blocks blood or other potentially infectious materials from reaching the wearer's skin, mouth, or mucous membranes · Keeps droplets and larger particles from being inhaled. Requires filtration of all air reaching the mouth/nose for 5 µm particles and larger Medical mask · Reduces the transfer of respiratory droplets to others · Blocks blood or other potentially infectious materials from reaching the wearer's skin, mouth, or mucous membranes · Keeps droplets and larger particles from being inhaled.
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From page 34... ...
The outermost layer (the third ply) is made of nonwoven, liquid-resistant, thermobond, polypropylene fabric designed to be the first contact filter barrier layer against body fluids and liquid particulate contaminants from outside the wearer's medical mask.
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. Medical Mask/N95 Filtering Facepiece Respirators Respiratory protection that combines the properties of surgical masks and respirators is known as a medical mask/N95 filtering facepiece respirator.
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From page 36... ...
or used nonapproved disposable facemasks available at hardware stores as a means of respiratory protection. Early reusable surgical masks were made of woven linen, which only redirected exhaled air away from the surgical wound.
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A structured framework or approach for the engineering design of textile structures involves understanding the specific require ments for the product (e.g., functionality, wearability, comfort, main tainability, durability, and affordability) , translating them into mea surable properties, identifying appropriate materials, selecting manufacturing technologies, and implementing processing param eters to achieve the specific requirements in the desired product (Rajamanickam et al., 1998)
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From page 38... ...
nurses entering a SARS patient's room did not consistently wear appropriate respiratory protection. None of these studies explored the reasons why specific individuals chose not to wear respiratory protection.
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have this additional feature and are certified by NIOSH as well as regulated by FDA. Medical masks and N95 filtering facepiece respirators are considered disposal devices and are not designed for either extended use or reuse after cleaning and disinfection.
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From page 40... ...
2004. Respiratory protection against Mycobacterium tuberculosis: Quantitative fit test outcomes for five type N95 filtering-facepiece respirators.
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From page 41... ...
1985. Face seal leakage of half masks and surgical masks.
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