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The Relationship of Fabric Properties and Bacterial Filtration Efficiency for Selected Surgical Face Masks


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Surgical face masks are an important component of surgical apparel. The masks are expected to perform as barriers and provide increased protection to the patients and health care workers. In this study, the Bacterial Filtration Efficiency (BFE) of six commercially available surgical face masks was determined for two microorganisms. Fabric characteristics (weight, thickness, pore size, and resistance to synthetic blood strike through) thought to influence the barrier effectiveness were measured and the relationship between these characteristics and BFE was examined. Two challenge microorganisms, Staphylococcus aureus and Escherichia coli were evaluated in this study. For five of the six masks evaluated, the BFE against the challenge microorganism S. aureus was higher than when the challenge microorganism was E. coli. The mask with the lowest mean pore size and lowest maximum pore size had the highest BFE for both microorganisms evaluated, indicating that a relationship exists between pore size and BFE.
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Article Designation: Refereed JTATM
Volume 3, Issue 2,Fall 2003
Volume 3, Issue 2, Fall 2003
The Relationship of Fabric Properties and Bacterial Filtration Efficiency for
Selected Surgical Face Masks
Karen K. Leonas, Ph.D. and Cindy R. Jones
Dawson Hall, University of Georgia
Athens, Georgia 30602
Surgical face masks are an important component of surgical apparel. The masks are expected to
perform as barriers and provide increased protection to the patients and health care workers. In
this study, the Bacterial Filtration Efficiency (BFE) of six commercially available surgical face
masks was determined for two microorganisms. Fabric characteristics (weight, thickness, pore
size, and resistance to synthetic blood strike through) thought to influence the barrier
effectiveness were measured and the relationship between these characteristics and BFE was
examined. Two challenge microorganisms, Staphylococcus aureus and Escherichia coli were
evaluated in this study. For five of the six masks evaluated, the BFE against the challenge
microorganism S. aureus was higher than when the challenge microorganism was E. coli. The
mask with the lowest mean pore size and lowest maximum pore size had the highest BFE for both
microorganisms evaluated, indicating that a relationship exists between pore size and BFE.
Keywords: surgical face masks, bacterial filtration efficiency, S. aureus, E. coli
Bacterial and viral diseases are spread
through both airborne and blood borne
pathways in the operating theater. Surgical
apparel can minimize the transmission of
disease. The transfer of microorganisms can
be reduced because the protective surgical
apparel creates a physical barrier between
the infection source and the healthy
individual.[1] A medical device intended to
be worn by operating room personnel during
surgical procedures to protect both the
surgical patients and operating room
personnel from transfer of microorganisms,
body fluids and particulate material is
identified as “Surgical Apparel” in 21 CFR,
Part 878.4040. The OSHA Occupational
Exposure to Blood Borne Pathogens: Final
Rule (1991) mandates the principles of
universal precautions, mandates
performance levels, and allows employers to
specify what personal protective equipment
is required and when it must be used.[2, 3]
Surgical face masks are an important
component of surgical apparel. The masks
are expected to perform as barriers and
provide increased protection to the patients
and health care workers. Initially, the
primary purpose of the facemask was to
protect the patient from being contaminated
by bacteria or viral species exhaled or
Article Designation: Refereed JTATM
Volume 3, Issue 2,Fall 2003
expelled from the health care worker.
Normal activities such as sneezing,
coughing, shouting, crying, breathing and
speaking may release oral, dermal and
nasopharyngeal bacteria that may cause
post-operative infections.[4] A second
purpose of the mask, that has emerged in the
past decade, is the protection for the health
care worker from exposure to blood borne
pathogens. Skinner and Sutton have
reported studies that show how surgeons
commonly receive blood and/or fluid
splashes to the face during operating room
In the past decade, a number of publications
have addressed the development and role of
the surgical face mask in the operating
theater, and its effectiveness in reducing
post-operative infections.[5, 6, 7, 8, 9, 10]
Research has shown that there are numerous
other methods by which bacteria become
airborne and that the microorganisms shed
by the healthcare team are the most
significant contaminating agents, even in
correctly designed operating rooms.[5]
Studies have also shown that the fit of the
mask, the proper positioning and use of the
mask, movement by the wearer, the length
of facial hair and voice level when speaking,
all have a direct bearing on its filtering
efficiency.[11, 12, 13]
Although the effectiveness of the face mask
for reducing surgical site infections has been
controversial, a number of major
organizations have published guidelines for
health care workers to minimize risks of
exposure which include face masks. They
include the Centers for Disease Control
[CDC], Association of Operating Room
Nurses [AORN], Occupational Safety and
Health Administration [OSHA] and the
Operating Room Nurses Association of
Canada [ORNAC]. AORN recommends
that “all persons entering restricted areas of
the surgical suite should wear mask when
open sterile items and equipment are
present” and that masks be worn along with
protective eyewear whenever exposures to
mucous membranes is reasonably
anticipated.[14] The Operating Room
Nurses Association of Canada (ORNAC)
agree with these recommendations.[15]
The CDC guidelines admit that the role of
face masks in reducing the risk of surgical
site infections may be more uncertain than
previously thought. And yet, the same
guidelines support the use of surgical face
masks as personal protective equipment.
In this regard the study of the transmission
of small particles and liquid aerosols
through nonwoven products used in
protective apparel and other filter media is
of importance. This area of study, with
reference to surgical face masks, is of
interest as masks are now expected to act as
protective barriers. In the summer of 2001,
several new ASTM standards specifically
relating to face masks and their evaluation
(ASTM-F2101-01; ASTM-F2100-01) were
approved.[16] In a draft document,
published in 1998, the FDA listed 5 major
categories of tests that are available for
determining the barrier performance and
safe use of a surgical mask. They were 1)
fluid resistance, 2) filtration efficiency, 3)
air exchange pressure (Delta P), 4)
flammability and 5) biocompatibility
In 1999 Davis reviewed the test methods
used for the evaluation of face masks
effectiveness [18]. Bacterial Filtration
Efficiency (BFE), both in vivo and in vitro,
is a widely accepted method of evaluating
face masks. In these tests, the bacteria
penetrating the face masks are collected,
cultured and counted to determine the
number of Colony Forming Units (CFU’S)
that penetrate the mask. The in vitro test
uses positive and negative controls to
determine the initial number of bacteria.
The challenge bacteria are contained in a
mist, which is produced by aerosolizing the
bacteria with 0.1% peptone water in a
nebulizer. The masks are placed directly
Article Designation: Refereed JTATM
Volume 3, Issue 2,Fall 2003
over the opening of an Anderson sampler.
The aerosol consists largely of droplets that
simulate expulsion from the wearer. The
current BFE tests are used with the
microorganism S. aureus. However there
are a number of microorganisms in addition
to S. aureus that are known to cause
nosocomial infections and other serious
health problems. Nosocomial infections,
which are defined as those infections
originating in the hospital or healthcare
center, occur in about 5% of all patients
admitted to the hospital, with 41% being
urinary tract infections, 18% surgical, and
16% respiratory.[19] Postoperative wound
infections occur in up to seven percent of
surgical patients and require patients to
remain in the hospital an average of 7.3
extra days at an additional average cost of
$3,152.[20, 21] Although a variety of
pathogens are encountered in the hospital
environment, a relatively limited number
cause the majority of hospital infections
including Escherichia coli, Pseudomonas
aeruginosa, Enterococcus faecalis, Candida
albicans, and Staphylococcus aureus.[20]
Microorganisms have varying characteristics
that can influence their potential ability to
penetrate the facemask material including
shape, size, and their surface characteristics.
A wide variety of studies have evaluated the
BFE of face masks, however there have
been a limited number of microorganisms
evaluated in these studies.[4,22,23]
Willeke, et. al reported that rod-shaped
bacteria penetrate less than spherically
shaped bacteria of similar size.[22] In
addition, few studies have evaluated the
BFE of the face masks with specifically
engineered fabric characteristics
In this study, the BFE of six commercially
available surgical face masks was
determined for two microorganisms, S.
aureus and E. coli. Fabric characteristics
that influence the barrier effectiveness were
measured and evaluated. Although the fit
of the mask and leaks between the face and
the mask interface are known to be
important performance considerations, they
have not been addressed in this study.
Materials and Methods:
In this study, two components of the FDA
recommended areas were evaluated, 1)
liquid resistance and 2) filtration efficiency.
Six commercial face masks, each from a
different manufacturer, were selected for
evaluation (Table 1). Three of the face
masks (#1-3) were three ply with a pleated
construction, and three (#4-6) were molded
face masks.
Properties that characterize the fabric, such
as thickness, weight, and pore size, were
measured in addition to the liquid resistance
and bacterial filtration efficiency. These
characteristics were determined in
accordance with standard testing procedures
(Table 2). Liquid barrier properties were
measured according to ASTM F-1862-98:
Standard Test Method for Resistance of
Medical Face Masks to Penetration by
Synthetic Blood. This test method is
designed to evaluate penetration of the
masks by synthetic blood under high
velocity. In this project varying degrees of
velocity were examined to determine the
influence of pressure on the level and
mechanism of transmission. Velocity spray
pressures of 80 mmHg, 120 mmHg, and 160
mmHg were selected.
The Bacterial Filtration Efficiency for each
mask was determined in accordance with
ASTM Test Method F2101-01, Evaluating
the Bacterial Filtration Efficiency (BFE) of
Medical Face Mask Materials, Using a
Biological Aerosol of Staphylococcus
aureus. Two bacteria were selected for
evaluation in this study, S. aureus and E.
Article Designation: Refereed JTATM
Volume 3, Issue 2,Fall 2003
Table 1: Face masks Descriptions
Mask Name Description
1 Tie-on Surgical Face Mask
3-ply, pleated rayon outer web with polypropylene inner
2 Classical Surgical Mask, Blue 3-ply, pleated cellulose polypropylene, polyester
3 Sofloop Extra Protection Mask
3-ply, pleated blended cellulosic fibers with polypropylene
and polyester, ethylene methyl acrylate strip
4 Aseptex Fluid Resistant Molded rayon and polypropylene blend with acrylic binder
5 Surgine II Cone Mask Molded polypropylene and polyester with cellulose fibers
6 Surgical Grade Cone Style Mask Molded polypropylene
Table 2. Test Methods and Procedures Used to Determine Facemask Properties
Description Method Number Title
Thickness ASTM D1777-96 Standard Test Method for Thickness of Textile Materials
Weight ASTM D3776 -96 Weight Per Unit Area
Pore Size PMI Automated Perm Porometer Operation Manual, Version 6.
Synthetic Blood
ASTM F1862-00a
Standard Test Method for Resistance of Medical Face Masks to
Penetration by Synthetic Blood
Bacterial Filtration
ASTM F2101-01
Evaluating the Bacterial Filtration Efficiency (BFE) of Medical Face
Mask Materials, Using a Biological Aerosol of Staphylococcus
S. aureus is a gram positive cocci that is
irregular in shape and often in grape like
clusters. Various diseases and ailments
including impetigo, toxic shock syndrome,
food poisoning and pneumonia are attributed
to S. aureus. An average coccus is about 0.5
- 1.0
µm in diameter. E. coli is a gram
negative, rod shaped bacteria and averages
1.1 to 1.5
µm in width by 2.0 to 6.0 µm in
length. E. coli is a leading cause of urinary
tract infections.
The percent BFE was determined as
described in the test method for S. aureus,
and modified for E. coli. The S. aureus was
obtained from American Type Culture
Collection #6538 and E. coli was obtained
from UGA Microbiology Department.
Tryptic Soy Agar was the media used and
Peptone water (Difco Dehydrated 500
grams-Lot #1361000) was used as the
diluting agent as needed for the test method.
Positive and negative controls were
Article Designation: Refereed JTATM
Volume 3, Issue 2,Fall 2003
completed for each replication as directed in
the test method. Using the positive control,
it was determined that a challenge delivery
rate of 2200 +/- 500 viable particles per test
was required. This was achieved by diluting
the bacterial stock solution to the
appropriate bacterial concentration. The rate
was determined by the results of the positive
control plates when the aerosol is collected
in the six-stage viable particle cascade
impactor, with no test specimen clamped
into the test system. The exposed plates
were placed in an incubator at 37
C for 24
hours. The CFU’s for each plate were
counted using the Protocol Bacteria Colony
Counter, Synopitcs Corporation, V 2.05.
The filtration efficiency percentages were
calculated using the equation provided in the
test method:
100 (C-T) / C = %BFE
where C = average plate count total for test
controls and T = plate count total for test
Results and Discussion
The fabric characterization results for the
three face masks are presented in Table 3.
The pleated masks had lower pore size
means than the molded masks. Mask #3 had
the lowest mean pore size, 16.9
µm, followed
by Mask #2 with a mean pore size of
µm, and Mask #1 had the highest pore
size of the pleated masks at 23.97
µm. The
mean pore size of the molded masks were
significantly higher ranging from 31.72
(Mask #6) to 51.0
µm (Mask #5). Although
thickness was not significantly different for
the masks, the basis weight ranged from
58.567 gm/m
(Mask #2) to 164.405 gm/m
for Mask #6. The molded masks (#4, 5 & 6)
were significantly higher in weight than the
pleated masks (#1, 2 & 3).
The percent Bacterial Filtration Efficiency
for each mask and bacteria are presented in
Table 4. For 5 of the 6 masks (not Mask
#4), the BFE values were higher when tested
with E. coli than for S. aureus. This was
expected as the size and shape of the
microorganisms differ and E. coli is larger
and rod shaped when compared with S.
aureus. S. aureus ranges in size from 0.5 to
1.0 microns and is round in shape. E. coli is
rod shaped and averages 1.1 to 1.5
µm in
width by 2.0 to 6.0
µm in length.
Mask #3 had the highest %BFE for S.
aureus and the second highest %BFE for E.
coli and the lowest mean pore size of the
face masks examined here. This indicates a
relationship between pore size and BFE and
further testing should be completed to
investigate this relationship.
Mask #3, also had the lowest maximum pore
size of 27.19
µm. This is a critical
parameter to measure as this indicates the
largest pore detected in the sample and
therefore particles may be transmitted
through this opening, hence reducing the
BFE. When considering the mean pore size
and the maximum pore size for face Masks
#1 and #2, their order from highest to lowest
is reversed for these two parameters.
Although Mask #2 had a lower mean pore
size than Mask #1, the maximum pore size
was greater than that of Mask #1. This may
help explain why the BFE for the masks is
not in the same order as the mean pore size.
Mask #2 had a slightly lower BFE for E. coli
(98.53%) and S. aureus (88.18%) than did
Article Designation: Refereed JTATM
Volume 3, Issue 2,Fall 2003
Table 3: Face Mask Material Characteristics- thickness, weight, pore size, Resistance to
Pore Size
Synthetic Blood Resistance
(% Passed)
Max. 80 mm
120 mm
160 mm
1 0.3345 66.908 23.97 41.74 70 0 0
2 0.2339 58.657 19.29 43.27 100 100 50
3 0.4417 95.775 16.90 27.19 100 100 100
4 0.6137 140.828 35.06 87.74 0 0 0
5 0.3607 145.760 51.00 146.60 0 0 0
6 0.4742 164.405 31.72 92.12 0 0 0
Table 4. Face Mask Bacterial Filtration Efficiency - Mean and (Standard Deviation)
Mask S. aureus - % BFE E. coli - % BFE
1 91.09
2 88.18
3 92.19
4 90.72
5 84.82
6 86.4
Mask #1 (E. coli, 97.26%; S. aureus
88.18%). The % BFE for Mask #4 for S.
aureus was higher than for Mask #2, which
was unexpected since the mean and
maximum pore size for Mask #2 was lower.
The BFE of six surgical face masks has been
measured by challenges from two
microorganisms, S. aureus and E. coli.
Although there were no significant
differences between the face masks, the
Article Designation: Refereed JTATM
Volume 3, Issue 2,Fall 2003
bacterium did have a significant influence
on the facemask performance. The BFE for
5 of the 6 masks exposed to E. coli was
higher than when exposed to S. aureus. This
was likely due to the size and shape of the
bacteria. S. aureus is round and ranges in
size from 0.5mm to 0.1 mm. E. coli is rod
shaped and is larger, with size ranging from
1.1 to 1.5
µm in width and from 2.0 to 6.0
µm in length. Continuing studies with
different microorganisms and face masks
with varied characteristics will provide
additional information on those factors that
influence facemask barrier performance. In
addition, the relationship between the mean
pore size, the maximum pore size and the
pore size distribution with BFE performance
should also be examined.
This research was funded in part through a
grant from the Georgia Agricultural
Experiment Station, regional project S-1002.
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... There are different kinds of atomizers used in practical applications, such as pressure, rotary, air-blast, air-assisted, electrostatic and ultrasonic. A very extensive discussion about this topic was presented by Lefebvre (1989), Michelson (1990) and Bailey (1988). The recent evolution of high-speed rotary bell sprayer has received growing industrial attention among other atomizers. ...
... An overview of the scientific literature that deals with two specific issues of atomization and the particles charging, which will be analyzed deeply in the current thesis, is presented in the following. Lefebvre (1989) discussed about various techniques of liquid sheet atomization into a spray. The development of the liquid sheet leads to disintegration into ligaments and then further surface disturbances produce droplets. ...
... A few particles with a very small size, lower than the critical droplet diameter, leak from the cover and penetrate. This critical diameter is based on the mask microstructure, varies between 27.19 μm and 146.6 μm as reported by Leonas and Jones (2003). ...
Full-text available
During the past two decades, the Electrostatic Rotary Bell Sprayers (ERBSs), because of their superior transfer efficiency (TE) and coating performance, lower environmental destructive effects and cost decrement, attract the attention of many researchers in the coating industry. In this thesis, we developed a 3D comprehensive Eulerian-Lagrangian algorithm in order to investigate the fundamental behaviors of the flow in an electrostatic rotary bell sprayer (ERBS) during the formation of the droplets and depositing on a target. This efficient extended algorithm contains a model for airflow field, spray dynamics, electric field, droplet charge, droplet trajectory tracking and wall film dynamics. The fluid-dynamics is simulated by solving the unsteady 3D compressible Navier-Stokes equations. Unsteady flow is computed by using a Large eddy simulation (LES) turbulence approach, while the motion of the particles is simulated by tracking the droplet size distribution approach. The algorithm is implemented under the framework of the OpenFOAM package. Creating an initial condition of the particle approach has been proposed that is matched with practical applications. The present work contains a systematic analysis of the recirculation zone length, the toroidal vortex, the overspray phenomena and the flowfield characteristics like mean velocity, pressure, turbulent kinetic energy and velocity fluctuation. Also, the presented results describe exact values for the size, distribution, velocity, and trajectory of the particles in the ERBS. These results are important for coating industries to optimize their working conditions. The effect of operational parameters like bell rotational speed, shaping air and paint flow rate, electrical charge values and droplet size distributions are considered precisely. The results indicate as a main operating parameter the air-paint flow rate with voltage level deeply affecting the spray shape. The effect of the bell rotational speed in comparison with other parameters is dominant. The paint spray distribution obtained in the present work is validated against coating experimental results with suitable accuracy. Investigation of the various primary and secondary breakup models is one of the main goals of this work to predict the droplet size more precisely. The Reitz-KHRT, Reitz-Diwakar, Pilch-Erdman and the newly modified TAB model are examined in order to predict the secondary breakup process in the ERBS. Here, the implemented wall film function is able to predict the transport in the boundary layer over the target. This study also presents a performance evaluation of the ERBS with a particular focus on droplet charge, electric field, ambient conditions with the implementation of a high-voltage control-ring field pattern effect into the fully turbulent airflow and by including the atomized droplets discrete phase. The results indicate that the new proposal of using a control-ring operation improves the performance and transfer efficiency (TE) of the ERBS, and it also helps to harmonize the direction of the charged paint droplets. Furthermore, a novel electrostatic spraying system by using high-voltage retractable blades or high-voltage adjustable control ring is also presented in the current study as a recent patent. Also, some other useful applications of the implemented code are presented. First, the modified spraying part of the code is used, leading to a deeper understanding of the saliva-disease-carrier droplets transmission mechanisms as an atomized droplets during sneezing, coughing, or even exhaling. This is particularly important to ensure safety conditions in the work environment. Second, the implemend electrical field that was added to the code is considered without injecting droplets to accurately simulate the plasma flow by using a multi dielectric-barrier-discharge (DBD) plasma actuator over a 3D-airfoil difference. This shows the versatility of the developed model.
... There may be differences in the composition of the product among manufacturers. Therefore, various face mask types and descriptions of them are presented in Table 2 [37]. ...
... The brands of different manufacturers and their descriptions[37]. ...
Recently, COVID-19 has appeared as an international pandemic, leading to serious risks for humans. Using face masks is one of the most common measures in a wide-ranging prevention program that could control the COVID-19 dissemination. Face masks are typically composed of non-biodegradable and non-renewable polymers based on petroleum, which are harmful to nature and lead to health problems. In the present study, disposable face masks, the use of which has increased due to the Covid-19 pandemic throughout the world and which cause environmental pollution, were divided into very small pieces and utilized as a modifier in the bitumen binder. Therefore, this study aimed to provide a solution to such a significant environmental problem. Five different ratios of waste mask and the single ratio of styrene–butadienestyrene (SBS) were added to the pure binder and the rheological, physical, and chemical properties of the modified binders were compared. The result showed that adding a waste mask and SBS to the pure bitumen caused increases in binders’ softening point and viscosity and reductions in the penetration value. Waste mask modifications were able to better maintain its elastic properties both at low stress and high-stress levels with increasing temperature. 3% SBS was the binder most affected by temperature rise. As a result, it has been determined that binders containing more than 2% waste mask have better performance characteristics than binders containing 3% SBS in terms of physical and rheological properties.
... However, studies have shown that masks are usually heavier than the recommendations suggest 17,26 and present a high variation between different materials. 27 This study shows that there is no correlation between grammage and both FE (Fig. 1b) and air permeability (breathability) of different materials. In addition, as shown in Fig. 1c, the higher values of grammage presented a low QF. ...
... The results were probably affected by the pore size distribution of the samples, as proposed by Leonas and Jones. 27 Smaller pores rendered better filtration for the cotton samples; however, they also decreased breathability. Aside from that, it is not expected that common cotton fabrics have great filtering capacity for small particles, as suggested by O'Kelly. ...
Objectives This study evaluates the performance of eight non-professional face masks sold in São Paulo, Brazil, to prevent aerial transmission of the SARS-CoV-2. Study design This was a case report with comparative testing. Methods The masks manufactured with different materials and designs were quantified according to their performance to prevent COVID-19 using two indicators: filtration efficiency (FE) and differential pressure. The fabric grammage and microscopy of the layers were analyzed to understand their influence on the performance indicators. Results The results show no correlation between grammage in the FE and increasing grammage can compromise breathability indicator. Masks manufactured with cotton widely commercialized during the pandemic have non-uniformized results in FE indicators. Conclusions There was no evidence between grammage and the number of layers in the FE indicator. The results pointed out that the layer's composition and the microstructure are the best way to evaluate the performance of non-professional masks used to prevent the aerial transmission of the SARS-CoV-2.
... However, there are also others, depending on their manufacture, that have polyethylene, vinyl, natural or synthetic rubber latex, and multilayer disposable gloves that are made of thermoplastic material that comprises a mixture of two or more ethylene-based polymers (Lin et al., 2015). In contrast, some common disposable masks (e.g., blue surgical masks and protective masks) are composed by 3 layers of some of the following materials, propylene, polyester, ethylene strips with acrylic binders (Leonas and Jones, 2003). In any case, it should be noted that a large amount of medical waste includes polypropylene (PP) and acrylonitrile butadiene styrene (ABS) because these are commonly used in the manufacture of implements for medical applications (Jahnke, 2020). ...
To prevent the COVID-19 transmission, personal protective equipment (PPE) and packaging materials have been extensively used but often managed inappropriately, generating huge amount of plastic waste. In this review, we comprehensively discussed the plastic products utilized and the types and amounts of plastic waste generated since the outbreak of COVID-19, and reviewed the potential treatments for these plastic wastes. Upcycling of plastic waste into biochar was addressed from the perspectives of both environmental protection and practical applications, which can be verified as promising materials for environmental protections and energy storages. Moreover, novel upcycling of plastic waste into biochar is beneficial to mitigate the ubiquitous plastic pollution, avoiding harmful impacts on human and ecosystem through direct and indirect micro-/nano-plastic transmission routes, and achieving the sustainable plastic waste management for value-added products, simultaneously. This suggests that the plastic waste could be treated as a valuable resource in an advanced and green manner.
... In this context, masks must be used in a well-fitting way, as contaminants can bypass the filtering effect of these, entering through their pores. Studies show that the proper fit and positioning of the mask, the operator's movement, as well as the voice level when speaking have a direct influence on the efficiency of bacterial filtration 32 . It has been shown that the severe acute respiratory syndrome (SARS) virus is easily spread through the aerosol due to its particle size (5-10 μm), and the same is true for the SARS-CoV-2 virus due to their structural similarity 33 . ...
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To investigate the dispersion and contamination of aerosols generated during coronal access performed by high-speed handpiece and ultrasonic device. To measure the aerosol dispersion, a red dye or an Enterococcus faecalis culture broth inside the bottle of the water system of the dental and ultrasonic unit were used. Bovine extracted teeth were allocated in six groups according to the coronal access: G1: diamond bur in high-speed handpiece (HS) with aspiration (A); G2: ultrasonic (US) inserts with aspiration; G3: combined coronal access with HS and US with aspiration; and G4, G5, and G6 were performed without aspiration (WA). The distance reached by the aerosol with the dye was measured in centimeters, and for environment contamination, agar-plates were arranged at standardized distances for counting colony-forming units (CFU/mL). The ANOVA followed by the Tukey tests were applied (α = 0.05). The coronal access with HS generated higher aerosol dispersion and contamination, even with simultaneous A (P < 0.05), while US generated less aerosol even WA (P < 0.05). The aspiration did not reduce the aerosol statistically. HS is a great source of aerosols in dental clinic during the coronal access and the use of US device should be encouraged.
... Hence, any recycling is complex due to the different nature of their components. In addition, there are variations in the use of materials and their final conformation, such as the combination of polypropylene with polyethylene to manufacture mask layers [68]. The separation of the mask components is one of the most significant limitations of recycling. ...
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The disposal of single-use personal protective equipment has brought a notable environmental impact in the context of the COVID-19 pandemic. During these last two years, part of the global research efforts has been focused on preventing contagion using nanotechnology. This work explores the production of filter materials with electrohydrodynamic techniques using recycled polyethylene terephthalate (PET). PET was chosen because it is one of the materials most commonly present in everyday waste (such as in food packaging, bags, or bottles), being the most frequently used thermoplastic polymer in the world. The influence of the electrospinning parameters on the filtering capacity of the resulting fabric was analyzed against both aerosolized submicron particles and microparticulated matter. Finally, we present a new scalable and straightforward method for manufacturing surgical masks by electrospinning and we validate their performance by simulating the standard conditions to which they are subjected to during use. The masks were successfully reprocessed to ensure that the proposed method is able to reduce the environmental impact of disposable face masks.
... Precisely these protective masks and the contaminants filtered/trapped therein including viruses present significant potential for virus detection via preconcentration at the surface of the mask material. Surgical masks are typically made of non-woven, i.e., blown or spun polypropylene fabric, and typically comprise three layers [11][12][13] . Few analyses of masks have been performed focusing on the evaluation of exhaled breath aerosols (EBA) 14,15 . ...
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The ongoing COVID-19 pandemic represents a considerable risk for the general public and especially for health care workers. To avoid an overloading of the health care system and to control transmission chains, the development of rapid and cost-effective techniques allowing for the reliable diagnosis of individuals with acute respiratory infections are crucial. Uniquely, the present study focuses on the development of a direct face mask sampling approach, as worn (i.e., used) disposable face masks contain exogenous environmental constituents, as well as endogenously exhaled breath aerosols. Optical techniques—and specifically infrared (IR) molecular spectroscopic techniques—are promising tools for direct virus detection at the surface of such masks. In the present study, a rapid and non-destructive approach for monitoring exposure scenarios via medical face masks using attenuated total reflection infrared spectroscopy is presented. Complementarily, IR external reflection spectroscopy was evaluated in comparison for rapid mask analysis. The utility of a face mask-based sampling approach was demonstrated by differentiating water, proteins, and virus-like particles sampled onto the mask. Data analysis using multivariate statistical algorithms enabled unambiguously classifying spectral signatures of individual components and biospecies. This approach has the potential to be extended towards the rapid detection of SARS-CoV-2—as shown herein for the example of virus-like particles which are morphologically equivalent to authentic virus—without any additional sample preparation or elaborate testing equipment at laboratory facilities. Therefore, this strategy may be implemented as a routine large-scale monitoring routine, e.g., at health care institutions, nursing homes, etc. ensuring the health and safety of medical personnel.
... Description of face mask ( Leonas et al., 2003 ). ...
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The current COVID-19 pandemic has significantly altered the quantity and composition of waste generated on the African continent. This new phenomenon, coupled with the indiscriminate disposal of used personal protective equipment (PPEs), poses serious challenges to local authorities, most of whom have limited experience or lack the strategy to handle this occurrence. These PPEs, like the face masks, are made up of polymeric materials that are liquid resistant and remain for a long time in the environment after discard. Thus, they are considered as a significant source of plastic pollution in the environment. Notwithstanding the environmental challenges associated with COVID-19, if Africa is to be ready for the expected growth in waste generation and variation in waste composition in the coming century as predicted by the African waste management outlook report in 2018, she has to have a renewed focus and seize the unique opportunities that COVID-19 presents. The continent has to indulge in introspection of its shortfalls in managing waste and consciously make efforts that would ensure social and technological innovation and investment in services and infrastructure in the waste and secondary resources sector than never before seen in Africa. This approach would help the continent achieve its waste management vision of extending regular and reliable waste collection services to all while valorizing waste generated. This critical review paper reveals the silver lining in the dark cloud of the COVID-19 pandemic by highlighting some of the noticeable environmental challenges in Africa due to the current pandemic and elucidating the rare opportunities that African countries can harness to improve the waste management sector.
... Description of face mask ( Leonas et al., 2003 ). ...
Purpose: This paper explores the consequences of the Covid-19 pandemic as far as some aspects of SDG 11 are concerned. From the experience of the pandemic, the paper further explored lessons and opportunities for addressing some aspects of SDG11.
With the outbreak of the COVID-19 pandemic, textile laundering hygiene has proved to be a fundamental measure in preventing the spread of infections. The first part of our study evaluated the decontamination efficiency of various treatments (thermal, photothermal, and microwave) for bio contaminated textiles. The effects on textile decontamination of adding saturated steam into the drum of a household textile laundering machine were investigated and evaluated in the second part of our study. The results show that the thermal treatment, conducted in a convection heating chamber, provided a slight reduction in efficiency and did not ensure the complete inactivation of Staphylococcus aureus on cotton swatches. The photothermal treatment showed higher reduction efficiency on contaminated textile samples, while the microwave treatment (at 460 W for a period of 60 s) of bio contaminated cotton swatches containing higher moisture content provided satisfactory bacterial reduction efficiency (more than 7 log steps). Additionally, the treatment of textiles in the household washing machine with the injection of saturated steam into the washing drum and a mild agitation rhythm provided at least a 7 log step reduction in S. aureus. The photothermal treatment of bio contaminated cotton textiles showed promising reduction efficiency, while the microwave treatment and the treatment with saturated steam proved to be the most effective.
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Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts upon all aspects of society and life.
In most modern hospitals, no one is allowed to enter the operating theatre without wearing a surgical face mask. The practice of wearing masks is believed to minimize the transmission of oro- and nasopharyngeal bacteria from operating theatre staff to patients' wounds, thereby decreasing the likelihood of postoperative surgical site infections. In this era of cost-restraints, shrinking hospital budgets, and evidence-based medicine, many health care professionals have begun to re-examine traditional infection control practices. Over the past decade, studies challenging the accepted dogma of surgical face mask usage have been published. Masks that function as protective barriers are another emerging issue. Due to a greater awareness of HIV and other blood-borne viruses, masks are taking on a greater role in protecting health care workers from potentially infectious blood and body fluids. The purpose of this review is to evaluate the latest evidence for and against routine use of surgical face masks in the operating theatre.
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