Disposable over Reusable Face Masks: Public Safety or
Joana C. Prata 1, *,† , Ana L. Patrício Silva 2 ,† , Armando C. Duarte 1and Teresa Rocha-Santos 1
Citation: Prata, J.C.; Silva, A.L.P.;
Duarte, A.C.; Rocha-Santos, T.
Disposable over Reusable Face Masks:
Public Safety or Environmental
Disaster? Environments 2021,8, 31.
Academic Editors: Göran Finnveden
and Dimitrios Komilis
Received: 22 February 2021
Accepted: 11 April 2021
Published: 13 April 2021
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1Centre for Environmental and Marine Studies (CESAM) & Department of Chemistry, University of Aveiro,
3810-193 Aveiro, Portugal; firstname.lastname@example.org (A.C.D.); email@example.com (T.R.-S.)
2Centre for Environmental and Marine Studies (CESAM) & Department of Biology, University of Aveiro,
3810-193 Aveiro, Portugal; firstname.lastname@example.org
† These authors contributed equally to this work.
Many governments have imposed the public use of face masks and they are now moving
towards enforcing disposable masks to abate COVID-19 transmission. While disposable masks consistently
provide higher protection, they also carry multiple environmental burdens, from greenhouse gases released
during production to the landfilling and littering. Conversely, reusable masks’ protection can vary from
>90% certified industrial masks, similar to disposable masks, to dubious homemade or artisanal masks.
This work discusses the protection provided by different masks, their impact on the environment, and
new proposals combining concerns about public health and sustainability.
SARS-CoV-2; personal protective equipment (PPE), cloth masks; fabric masks; surgical
masks; medical masks; respirators
The COVID-19 pandemic, transmitted by respiratory droplets [
], increased the global
demand for face masks (herein masks) used by healthcare professional and the general
population as a measure to reduce viral transmission, in pair with social distancing and
hygiene. Depending on cultural and economic factors, disposable or reusable masks have
been voluntarily or compulsory adopted by the public [
]. Disposable masks refer to
loose-ﬁtting surgical masks and well-ﬁtted respirators (e.g., N95) with ﬁltration efﬁciencies
characterized as FFP1 (80%), to FFP2 (94%), and FFP3 (99%) in Europe and N95 (95%), to
N99 (99%), and N100 (100%) in the US [
]. Disposable masks are made of polypropylene
(PP) and high-density polyethylene (HDPE) used in the production of nonwoven fabrics
using a melt-blown process [
]. Some of these FFP devices are classiﬁed as reusable
(marked with “R”) [
]. Conversely, reusable textile masks are highly available at low-
cost, varying in quality from homemade or artisanal, to industrial productions subjected
to certiﬁcation. However, the rise in virus variants with increased transmissibility [
raised concerns over the public use of reusable masks, considering the wide variation
in protection efﬁciency. For instance, only 20% of over 3000 certiﬁed reusable masks in
Portugal had ﬁltration efﬁciencies >90% [
]. Facing these new strains while attempting
to avoid economic disruption caused by lockdowns and the overloading of public health
systems, many countries (e.g., France, Austria, and Germany) are enforcing the use of
disposable masks in numerous public spaces [
]. Restrictions on the use of reusable masks
in public spaces have not considered their diversity and variable protection. Considering
the estimated global use of 129 billion disposable masks per month [
], it is urgent to
understand the scientiﬁc foundations supporting the use of disposable over reusable
masks, the repercussions of these measures, and potential workarounds which can favor
sustainability without compromising public health. This manuscript provides an overview
on protection efﬁciency, environmental impacts, and recommendations on disposable and
reusable masks for public use.
Environments 2021,8, 31. https://doi.org/10.3390/environments8040031 https://www.mdpi.com/journal/environments
Environments 2021,8, 31 2 of 10
2. Protection Efﬁciency of Disposable and Reusable Masks
Transmission of SARS-CoV-2 mainly occurs through airborne droplets (5–10
and aerosols (
m), including from asymptomatic individuals or before the onset of
]. Masks can reduce the release of particles and protect the wearer [
]. After a
ﬁrst stage of global personal protective equipment (PPE) shortage, public use of masks has
been recommended or enforced in several countries to prevent community transmission of
SARS-CoV-2 virus [
]. Indeed, no coronavirus could be detected in respiratory droplets
and aerosols of patients wearing surgical masks compared to 30–40% of samples of patients
without masks [
]. Community mask use to reduce COVID-19 transmission is supported
by a study following over 300,000 individuals in the US [
] and reduced household
transmission in Beijing, China [
]. While mask use became the norm, the protection
provided by different solutions has only recently attracted governmental attention.
Studies on the efﬁciency and protection conferred by masks are conducted in three
major types: reusable (or cloth) masks, surgical masks, and respirators. For Inﬂuenza virus,
also transmitted by respiratory droplets and aerosols, both respirators (N95) and surgical
masks were effective in preventing the spread of the virus from infected patients  and
in preventing infection of healthcare workers working in outpatient settings [
]. While all
masks are protective for Inﬂuenza, homemade masks produced from tea clothes provided
two times less protection than surgical masks and 50 times less than FFP2 respirators [
Similarly, surgical masks presented better ﬁltration efﬁciency and generally reduced the
total amount of microorganisms expelled by coughing, compared to homemade masks
of different materials [
]. For COVID-19, a surgical mask barrier signiﬁcantly reduced
transmission or produced fewer clinical manifestations in Golden Syrian Hamster [
Centers for Disease Control and Prevention (CDC) recommends general use of cloth masks,
ideally of multiple layers of high-thread-count textiles, which can block up to 50–70% of
ﬁne droplets and particles and are reported to reduce transmission in multiple settings [
However, a metanalysis of betacoronavirus (including SARS-CoV-2) concludes that, while
all masks are effective at preventing transmission, respirators (e.g., N95) are more protective
than disposable medical masks or reusable cotton masks (12–16 layers) [
]. In summary,
all masks can contribute to the reduction of COVID-19 transmission, but higher protection
can be achieved by using respirators, followed by surgical masks, and ﬁnally reusable or
Compared to no mask, a modeling study showed that even moderately effective masks
(50%) worn by 80% of the population could prevent 17–45% of deaths over 2 months in
New York, US [
]. Thus, reusable masks, even if moderately effective, can be a useful tool
to control the pandemic, especially when coupled with social distancing and hand hygiene.
Moreover, most works have not considered the diversity of reusable masks available in
regard to their quality. Recommendations regarding homemade mask making include
selection of proper fabrics, using multiple layers (>2–3), choosing a design with a proper
seal around the face, and using ﬁtting ear loops . A review on cloth masks found that,
generally, textiles >300 TPI (threads per inch) had ﬁltration efﬁciencies above 80% and rec-
ommends the use of cotton or ﬂannel of at least 100 TPI in at least two layers [
multilayer masks combining a layer of 600 TPI cotton with two layers of silk, two layers of
chiffon, or one layer of ﬂannel, by providing physical and electrostatic ﬁltering, produced
efﬁciencies of >90%, comparable to those achieved by N95 respirators [
humidity released by breathing (i.e., 99% relative humidity) increases particle capture in
100% cotton fabrics, increasing ﬁltration efﬁciency by 63% for 825 nm particles [
characteristics should also be tested in terms of wearability, such comfort, breathing effort,
and thermal conductivity, to ensure extended use without removal [
]. Thus, reusable
masks can provide effective and reliable protection comparable to disposable masks if
produced following rigid quality standards. Testing standards for disposable masks can be
applied to reusable masks (e.g., EN 14683:2019+AC:2019; see Reference [
certiﬁed reusable masks generally have efﬁciencies of ﬁltration of 3
m particles >70% or
>90%—in the last case, similar to surgical masks .
Environments 2021,8, 31 3 of 10
The efﬁciency of masks also depends on their correct use. Reusable masks may be
subjected to longer periods of use, multiple reuses without cleaning, ineffective cleaning
procedures, or decreased protection by exceeding the recommended number of washings.
Similarly, disposable masks, which should be used for 3–4 h, can be used for longer periods,
improperly stored (e.g., in pockets), and reused. For both, incorrect use and manipulation
can increase the risk of transmission. Besides ﬁltration efﬁciency and use, the design of
both disposable and reusable masks should reduce face-seal leakage (i.e., by proper sealing
around the face), preventing the inward leakage of ambient aerosols and thus exposure to
infectious agents. For instance, N95 respirators present lower inward leakage compared
to generally loose-ﬁtting surgical masks [
]. Face-seal leakage highly inﬂuences mask
performance, which is not often accounted for when assessing the efﬁciency of facemask
materials, with increased ventilation resistance and mask gap dimensions hindering pro-
tection (e.g., gaps of 1.5% of mask area can result in a 20% bypass of unﬁltered air) [
Therefore, both disposable and reusable masks should be designed to reduce face-seal
leakage. Reusable masks have the additional problem of including homemade or artisanal
masks with varying efﬁciencies and not complying with quality standards. When it comes
to selecting face masks, design and fashion of reusable masks often outweigh functionally
in the consumer’s eyes. Additionally, reusable masks may be preferred by lower income
families due to their low-cost, as they can be 3.7 times cheaper than disposable masks [
In Portugal, the monthly cost of wearing two FFP2 masks per day (0.7–1.9
]) is 42–114
per person. Therefore, the obligatory use of FFP2 masks increases social injustices in the
access to public and workspaces, while further straining the budget of low-income families.
3. Environmental Impact of Disposable and Reusable Masks
Reusable masks have been recommended as safe and ecofriendly alternatives [
with the implementation of the obligatory use of disposable masks worsening environ-
mental problems, from production to disposal. However, the environmental impact of
reusable masks relies on their type and the use behavior and mask choice by common
citizens (i.e., reusability, times of reuse, type of washing, and use of ﬁlters or not). For
instance, in an estimation based on UK yearly use of masks, Allison et al. [
similar environmental footprint between of reusable masks to the surgical masks, when
considering the use of ﬁlters and manual washing of reusable masks (
eq), but lower in reusable masks without ﬁlters and machine washed (1.7
Conversely, reusable masks without ﬁlters and machine-washed have a greater water use
than disposable masks, due to the washing process (7.5
gas (GHG) emissions of producing cotton cloth masks are similar to surgical masks (~0.06
eq/pcs), but increases to 6.92 kg CO
eq/pcs considering washing (as reviewed
by Reference [
]). However, the estimation of cotton cloth masks has not considered the
transportation emission that is accounted for surgical masks. However, if a reusable mask
could be used for 183 times (without the use of disposable ﬁlters and considering cleaning
in the washing machine with regular clothes), the environmental footprint would go down
to 0.04 kg CO
]. However, the cumulative effects of washing can contribute to the
degradation of the mask material and reduced protection. Reusable masks can be made of
synthetic materials (e.g., polyester), which can reduce emissions and improve the number
of reuses. In addition, an adequate use and cleaning of reusable masks seems to reduce
waste by 85% and have a lower impact on climate change by 3.5 times, while also being 3.7
times cheaper [
]. However, information regarding ﬁber release during washing and their
ﬁnal disposal is still lacking [
]. After use, both disposable or reusable masks should be
disposed of as municipal solid waste, ideally double-bagged, to be preferably incinerated
or landﬁlled [
]. Alternatively, a new waste stream can be created to collect and treat PPE,
reducing the amount of litter requiring treatment [
]. While incineration (800–1000
decontaminates waste, with potential for energy production, these infrastructures may
already be overburdened by the growing medical waste [
]. Most COVID-19 household
waste is being landﬁlled [
] or, worse, discarded in open landﬁlls in countries with limited
Environments 2021,8, 31 4 of 10
resources for proper waste management (e.g., Thailand, Philippines, and India), creating
both an environmental and public health problems [
]. In addition to the release of green-
house gases, landﬁlling of wastes may generate microplastics which are present in landﬁll
leachates and may be released to the surrounding environment [
]. In landﬁlls’ anaerobic
environments, plastics from masks degrade forming microplastics due to variations in
temperature and pH, physical stress, and competitions, as well as action of microbiological
activity, which contributes to a progressive degradation and formation of microplastics [
while degradation in open dumps occurs from sunlight exposure and methanotrophic
microorganisms’ activity at a faster rate than in soil [
]. Recycling of PPE is challenging
because it may require previous decontamination (e.g., by UV light; see Reference [
because items are composed of multiple polymer types which cannot be easily separated
by routine grinding and remelting. Other recycling solutions can be applied to masks,
such as in the production of thermoset composites, using a crosslinking compatibilizer
agent to overcome the presence of multiple polymer types [
] or by thermal-recycling
producing feedstock containing useful chemicals or liquid fuels, which then can be used in
the production of other materials or as energy [
]. These solutions could pair public
health measures with the progression towards a circular economy less reliant on landﬁlling.
In addition to challenges posed by waste management, many masks are littered and
released directly to the environment (Figure 1). In Morocco, 9% of survey respondents
admitted to disposing of masks in public spaces [
], while littered PPE dominated by
masks has been found in urban areas with densities of 0.001 item m
in Canada [
<0.3 item m
in Kenya [
]. While densities are dependent on sampling areas (e.g., higher
concentrations can be found near hospitals, [
]), littered items can vary with culture, with
disposable masks being a less relevant category of COVID-related litter in South Africa, due
to the widespread use of reusable cotton masks [
]. Beaches, which improved in quality at
the beginning of the pandemic [
], are now tainted with PPE, with this category compris-
ing up to 55.1% of anthropogenic beach litter in urban beaches in Kenya [
this litter is not found in coastal surface trawls, suggesting preferential accumulation on
beaches or the seabed after sinking [
]. PPE is also transported by rivers, comprising
16.0% of items in Jakarta rivers from March to April of 2020, with a high predominance of
facemasks (9.8%) [
]. Moreover, urban infrastructures are being burdened by PPE, with
littering and incorrect disposal into wastewater systems increasing maintenance costs by
$250 million a year in Canada [
]. The fate of littered PPE depends on their characteristics
in the environment, varying with brands and products, such as polymer density [
Degradation of nonwoven materials is likely to generate synthetic micro- and nanoﬁbers
when exposed to environmental conditions [
], as ﬁbers are released during mask use and
even potentially inhaled [
]. In the environment, weathering of plastics mainly occurs by
photo-oxidation by exposure to solar UV radiation, and at a slower rate by biodegradation
and hydrolysis, while posterior mechanical forces can lead to the formation of cracks
and fragmentation or delamination of smaller pieces, originating microplastics which
accumulate in the environment [
]. While larger plastics can lead to entanglement and
starvation after ingestion, microplastics can cause oxidative stress originating mortality,
reproductive failure, and decrease growth and feeding, in addition to being vectors to other
contaminants and microorganisms, having a negative impact on ecosystems .
Environments 2021,8, 31 5 of 10
Incorrect disposal of masks observed in Portugal: (
) disposable masks on a beach and (
) reusable mask on an
4. Recommendations on the Use of Disposable and Reusable Masks
As previously discussed, surgical masks and respirators consistently performed better
than tested reusable masks. While this supports the phasing of reusable masks, perfor-
mance and reliability also varies within categories (i.e., from artisanal to certiﬁed industrial
reusable masks), and many misuses are shared with disposable masks (e.g., multiple
reuses). Disposable masks present environmental challenges, from the release of green-
house gases during production, to the amount of waste generated or littering of public
spaces. Reusable masks are also not devoid of environmental impacts, depending on their
type and consumption patterns. Considering that both choices have different consequences,
favoring disposable or reusable masks falls over the priorities determined by governments.
More information on day-to-day protection provided by disposable and reusable masks,
conditioned by their correct use (e.g., correct face seal and proper washing), as well as
the speciﬁc environmental impacts for each type and scenario (e.g., depending on waste
treatment; microplastic release during use, washing, and disposal) can clarify the pros and
cons of each mask type. Nonetheless, various strategies can be adopted to couple public
health with long-term environmental sustainability:
Reusable masks can be produced to achieve protection efﬁciencies >90%, similar to
disposable masks (e.g., by using speciﬁc fabric combinations to enhance electrostatic
and physical ﬁltering [
]). In Portugal, 20% of certiﬁed reusable masks already
provide protection >90% [
], proving that it is possible to achieve high protection efﬁ-
ciencies. Additionally, face-seal leakage should be reduced in any mask by including
metal nose and face pinches [
], applying a thermoplastic rings or braces over the
], simply by knotting the ear loops [
], or improving design. Moreover,
color-changing sensors can be used to reduce the misuse of reusable masks. For in-
stance, photochromic systems can monitor the length of use of the masks by reversibly
developing color when exposed to light, while thermochromic systems can be used
to monitor proper decontamination under high temperatures, by fading color [
Additionally, antiviral materials (e.g., with non-adhesive surfaces or nanostructures),
capable of eliminating the virus on their surfaces while being safe for the wearer,
can also be developed and applied to improve the protection provided by reusable
]. Masks capable of inactivating SARS-CoV-2 and which retain their efﬁcien-
cies after 50 washes are already being commercialized in Portugal [
]. Reusable masks
following these manufacturing recommendations can be considered equivalent to
disposable masks, but they are still dependent on correct use and cleaning. However,
the implementation of novel technologies on reusable masks should be accompanied
by the evaluation of environmental footprint. To reduce the environmental footprint
of cotton reusable masks, its major component should be cotton that is rain-fed (there-
Environments 2021,8, 31 6 of 10
fore lowering the water footprint) or organically grown cotton (lowering the carbon
footprint in the absence of pesticides and fossil fertilizers). Another solution could be
the use of recycled cotton, or other types of materials, such as polyester. An increase in
lifespan, a decrease in weight, and machine-washing procedures for cleaning (rather
than handwashing) can also reduce the environmental footprint of reusable masks.
Furthermore, the environmental impact of reusable masks (and general PPE) could be
reduced by increasing local manufacture (rather than importing/shipping supplies)
and by rationalizing their use and cleaning processes. Moreover, safe reusable masks
design must appeal to consumers to discourage the use of artisanal masks.
Production of disposable masks may follow more sustainable practices to offset their
environmental impacts. These include the use of plastics produced from renewable
resources, the use of renewable energy in the manufacturing and transportation, and
proper disposal. As an example, a successful ﬁltering media has been of wheat gluten
biopolymer, a by-product of the food industry [
]. However, cost and scaling of biore-
ﬁneries may limit these novel applications in the short-term [
]. Speciﬁc life-cycle
assessments can be created to assess and mitigate environmental impacts. Disposable
masks can also be reused after proper decontamination treatments while maintaining
protection efﬁciency, further reducing environmental impacts. For instance, decon-
tamination of N95 masks can be achieved by steaming without loss of protection [
Reuse of disposable masks could help decrease their environmental footprint and cost.
Reusable masks should be subjected to standardization similar to disposable masks.
For instance, they could follow the same ASTM Standards [
] or require full certi-
ﬁcation regarding their efﬁcacy over a known number of washings, which may be
found in a national list (e.g., see Reference [
]). Standardization should also include
face-seal leakage requirements for both disposable and reusable masks. The use of
non-approved masks must be discouraged, which may vary from public awareness to
banning this practice by applying ﬁnes to their wearers or sellers. To ensure compli-
ance, a certiﬁcation mark can be included in a visible area of the mask. In addition,
all manufacturers should provide information about the materials used in each layer
(composition, weave, weight, and thread count), the number of layers [
], and face-
seal leakage. Recommendations regarding decontamination must also be provided.
Instead of generally enforcing the use of disposable masks, these can be specially
enforced only in high-risk situations, such shared indoor environments (e.g., hospitals,
offices, shops, and markets), while maintaining reusable masks in lower-risk situations
(e.g., walking outside). For instance, in Austria, FFP2 masks are already required in
transit, businesses, market, and carpooling [
]. Similarly, the World Health Organiza-
tion recommends reusable masks, except in suspected cases, those caring for COVID-19
infected, people over 60, and those with underlying conditions which increase risk [
Moreover, the effects of the widespread use of disposable masks on daily incidence of
disease in specific situations can be modeled, maximizing their benefits.
When implementing the obligatory use of disposable masks, and considering their
higher costs, availability in stores and equal access must be guaranteed, especially for
lower-income families. Otherwise, this measure can increase social injustices. State
co-payment, such as often applied to pharmaceutical products, can be implemented
in these cases, considering the importance of masks for public health. For instance,
people over 60 or with chronic conditions in Germany will receive FFP2 masks [
Besides medical-risk groups, low-income families should also receive masks.
Masks and other PPEs should be collected in proper containers for end-of-life re-
purposing or incineration. Collection can be made in sealed speciﬁc-colored bags
for door-to-door collection or in speciﬁc bins distributed in public places, allowing
for separation and speciﬁc treatment [
]. PPE-bins have already been installed in
Montreal, Canada, and in Guimarães, Portugal [
]. Separation also allows for
speciﬁc treatment (e.g., incineration and recycling) of PEE waste.
Environments 2021,8, 31 7 of 10
Recycling of disposable masks can be achieved by thermo-recycling [
] or by pro-
ducing composites (e.g., conducted by companies such TerraCycle and UBQ Materials;
see References [
]). When recycling is not feasible, incineration is preferred since it
eliminates pathogens and avoids landﬁlling. Due to the large amount of waste requir-
ing incineration (e.g., medical waste), countries may need to increase their treatment
capacity, either by involving private companies or having backup incinerators, or at
least having sufﬁcient waste-storage spaces.
Public awareness and education can provide tools on the proper use and disposal
of masks. Awareness programs can support the use of certiﬁed reusable masks and
their proper decontamination. Additionally, it may encourage the correct disposal
of masks after use and advertising for the public health and environmental dangers
of incorrect disposal of masks. Targeted actions may be applied to areas where the
incorrect disposal of masks is more likely to happen (e.g., near hospitals and grocery
shops; see Reference ).
J.C.P., conceptualization, project administration, visualization, writing-
original draft, and writing—review and editing. A.L.P.S., conceptualization, project administration,
visualization, writing—original draft, and writing—review and editing. A.C.D., supervision, project
administration, funding acquisition, and writing—review and editing. T.R.-S., conceptualization,
supervision, project administration, funding acquisition, and writing—review and editing. All
authors have read and agreed to the published version of the manuscript.
Thanks are due to FCT/MCTES for the ﬁnancial support (UIDP/50017/2020+UIDB/50017/2020),
through national funds. This work was also funded by Portuguese Science Foundation (FCT), through
the scholarship PD/BD/135581/2018 and the research contract CEECIND/01366/2018, under POCH
funds, co-ﬁnanced by the European Social Fund and Portuguese National Funds from MEC.
Conﬂicts of Interest: The authors declare no conﬂict of interest.
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