Global face mask pollution: threats to the environment and wildlife, and potential solutions

Face masks and protection against COVID-19 and other viral respiratory infections: Assessment of benefits and harms in children

Mask mandates for children were implemented at schools and childcare centers during the COVID-19 pandemic, and the US continues to recommend masking down to the age of two in certain settings. Medical interventions should be informed by high-quality evidence and consider the possibility of harm (i.e., include harm-benefit analyses). In this review, we weigh the existing evidence for the effectiveness of mask mandates to protect against COVID-19 and other viral respiratory infections and the harms associated with face mask wearing in children. There is a lack of robust evidence of benefit from masking children to reduce transmission of SARS-CoV-2 or other respiratory viruses. The highest quality evidence available for masking children for COVID-19 or other viral respiratory infections has failed to find a beneficial impact against transmission. Mechanistic studies showing reduced viral transmission from use of face masks and respirators have not translated to real world effectiveness. Identified harms of masking include negative effects on communication and components of speech and language, ability to learn and comprehend, emotional and trust development, physical discomfort, and reduction in time and intensity of exercise. Effectiveness of child masking has not been demonstrated, while documented harms of masking in children are diverse and non-negligible and should prompt careful reflection. Recommendations for masking children fail basic harm-benefit analyses.

Chalcogenide Materials in Water Purification: Advances in Adsorptive and Photocatalytic Removal of Organic Pollutants

Chalcogenide-based materials, known for their unique physicochemical properties, emerge as promising solutions for the removal of hazardous organic pollutants, such as dyes, pharmaceuticals, pesticides, and herbicides, from water and wastewater. This review examines the latest developments in the synthesis, structural optimization, and application of chalcogenide materials for environmental remediation. The past decade has witnessed remarkable advances in controlling the composition and structure of chalcogenide materials at the atomic level. The development of precise synthetic methods enables the creation of complex hierarchical structures, heterojunctions, and hybrid materials, leading to significant improvements in photocatalytic efficiency, stability, and selectivity for various environmental applications. Key emphasis is placed on adsorption and photocatalysis as green technologies, offering efficient pathways for pollutant removal. Mechanistic insights into the interactions between chalcogenide materials and contaminants are explored, providing a comprehensive understanding of their performance. Furthermore, challenges such as toxicity, scalability, and operational stability are discussed alongside future prospects for integrating these materials into industrial-scale water treatment systems. This review aims to inspire continued innovation in sustainable water purification technologies using chalcogenides.

Development of a Color-Changing Face Mask for Fever Detection Applications

This study focused on developing a color-changing fabric face mask for fever detection. Reversible Thermochromic Leuco dye (RTL) was applied as an indicator to alert wearers of elevated body temperatures, with the color change occurring at 37.5 °C. Five fabric types Polyethylene (PE), cotton (CO), a cotton-polyester blend (TC), polyester (PL), and Polyamide (PA) were coated with blue RTL to evaluate their color change responsiveness. The results showed that fabrics with higher thermal conductivity (λ), thermal absorptivity (b), and heat flow (q) exhibited faster color transitions. RTL-coated PE fabric demonstrated the best performance, with a thermal absorptivity of 312.8 Ws0.5m-2K-1 and a heat flow of 2.11 Wm-2, leading to a rapid color-change time of approximately 4.20 s. Although PE fabric had a lower thermal conductivity (57.6 × 10-3 Wm-1K-1) compared to PA fabric 84.56 (10-3 Wm-1K-1), the highest thickness 0.65 mm of PA fabric slowed its color-change reaction to 11.8 s. When selecting fabrics for optimal heat transfer, relying solely on fiber type or thermal conductivity (λ) is insufficient. The fabric's structural properties, particularly thickness, significantly impact thermal resistance (γ). Experimental results suggest that thermal absorptivity and heat flow are more effective criteria for fabric selection, as they directly correlate with color-change performance.

Polymers Used in Transparent Face Masks-Characterization, Assessment, and Recommendations for Improvements Including Their Sustainability

By 2050, 700 million people will have hearing loss, requiring rehabilitation services. For about 80% of deaf and hard-hearing individuals, face coverings hinders their ability to lip-read. Also, the normal hearing population experiences issues socializing when wearing face masks. Therefore, there is a need to evaluate and further develop transparent face masks. In this work, the properties of polymers used in ten commercial transparent face masks were determined. The chemical composition of the polymers including nose bridges and ear loops was determined by FTIR spectroscopy. The focus of the characterizations was on the polymers in the transparent portion of each face mask. In half of the masks, the transparent portion contained PET, while in the other masks it consisted of PETG, PC, iPP, PVC, or SR (silicone rubber). Most masks had been coated with anti-fog material, and a few with scratch-resistant compounds, as indicated by XRF/EDX, SEM/EDX, and contact angle measurements. Thermal, molecular weight, and mechanical properties were determined by TGA/DSC, SEC, and tensile tests, respectively. To measure optical properties, UV-Vis reflectance and UV-Vis haze were applied. An assessment of the ten masks and recommendations to develop better transparent face masks were made, including improvement of their sustainability.

Silk Nanofibrillar Aerogel as Sustainable Filters for Environmental Purification

Environmental pollution threatens human health and ecosystem sustainability, boosting a huge demand for filters. However, the petroleum-based filters are likewise environmentally hazardous since their non-degradability results in disposal in landfills. Although biodegradable synthetic polymers have been contemplated as alternative filtration materials, their utilization in fabricating ultrafine fibers to construct effective 3D filters remains an obstacle. In this study, all-biomass nanofibrous filters are developed with versatility and biodegradability based on silk nanofibrils (SNFs). Bulk aerogels with tunable structures can be fabricated through solvent-mediated ice crystal growth by using SNFs as a building block. The SNF-based aerogel exhibited excellent water purification performance, as evidenced by their ability to remove micro-nano plastics, organic dyes, and heavy metal ions. The practicability of this filter system is demonstrated by the successful production of purified water from simulated polluted water and dirty river water. Moreover, the versatility of the SNF aerogel is further proven by superior air filtration performance against PM0.3 and oily smoking. Furthermore, the SNF aerogel filter has a low environmental impact as it can be safely biodegraded in the natural environment, with a ratio of 73.8% after one year of landfill. This work provides a path toward sustainable purification treatment of environmental pollution.

Understanding the mechanism of water splitting on (111) and (001) surfaces of CsPbI2Br: time-domain ab initio analysis and DFT study

Photochemical splitting of water is a promising source of clean and sustainable energy. Perovskites are increasingly being used as photocatalysts. In this paper, we have presented nonadiabatic quantum dynamics simulations (NAMD) and ab initio simulation studies of photocatalytic splitting of water on the (111) and (001) surfaces of CsPbI2Br. The simulations not only helped identify the surface on which splitting occurred but also provided atomistic insights into this behavior. We proposed a three-step reaction mechanism, comprising photogeneration of charge carriers, followed by hole transfer from the iodine atom to water and splitting of water at the interface. Subsequent to water splitting, a hydrogen bond was formed between H and I. The splitting occurred due to the shifting of p-orbitals of the oxygen atom in the presence of light. We have computed the charge carrier lifetime on the (111) and (001) surfaces. The overlap integral between the conduction band minima (CBM) and valence band maxima (VBM) was suppressed on the (111) surface compared to that on the (001) surface. As a result, charge carriers remained separated for a longer time on the (111) surface and could participate in the water splitting process.

Environmental impact of disposable face masks: degradation, wear, and cement mortar incorporation

Polypropylene (PP) disposable face masks (DFMs) are essential for limiting airborne infectious diseases. This study examines the behavior of DFMs under three scenarios: (i) exposure to the natural environment, (ii) simulated high-energy aquatic environments through an abrasion test, and (iii) incorporation into cement-based mortars. In the natural weathering experiment, after 117 days, the DFMs exhibited photodegradation, resulting in chemical alterations in carbonyl and hydroxyl groups. This degradation led to the breakdown of the polymer and the release of microplastics and nanoplastics. Controlled abrasion tests, conducted in a Denver ball with water, sand, and ceramic balls for 2 h, confirmed that water is a critical factor for fiber release from DFMs. These tests resulted in the release of 0.26 g of PP fibers from 20 DFMs (weighing 62 g in total) with a diameter of 20 µm. Weathering and abrasion tests indicated rapid release and degradation of microplastics and nanoplastics, underscoring the importance of pursuing actions like reuse. Ecotoxicological tests revealed that leachates from the DFM-incorporated mortars showed no adverse effects on Daphnia magna or Selenastrum capricornutum, unlike the reference mortar, which caused substantial toxicity to Daphnia magna. Incorporating PP fibers from DFMs into cement-based mortars showed promising potential, as indicated by favorable ecotoxicity and chemical leaching test results.

Sterilization and Filter Performance of Nano- and Microfibrous Facemask Filters - Electrospinning and Restoration of Charges for Competitive Sustainable Alternatives

Facemask materials have been under constant development to optimize filtration performance, wear comfort, and general resilience to chemical and mechanical stress. While single-use polypropylene meltblown membranes are the established go-to material for high-performing mask filters, they are neither sustainable nor particularly resistant to sterilization methods. Herein an in-depth analysis is provided of the sterilization efficiency, filtration efficiency, and breathing resistance of selected aerosol filters commonly implemented in facemasks, with a particular focus on the benefits of nanofibrous filters. After establishing a general overview over face mask filters and machine washing parameters required for successful decontamination, respective changes in filter performance and structure are presented. Sustainably manufactured, highly efficient, but also more fragile electrospun membranes not only offer competitive performance as well as a more environment-friendly production and degradation process, but also support a subsequent sterilization and recharging approach via alcohol exposition and drying in an electric field. It is further elaborated on the prospective sustainability of each material to offer a clear outlook on electrospun membranes as the most promising filter membranes of the future.

Electret Nonwoven Structures for High-Efficiency Air Filtration, Produced Using the Blow Spinning Technique

This study explores the fabrication of electret nonwoven structures for high-efficiency air filtration, utilizing the blow spinning technique. In response to the growing need for effective filtration systems, we aimed to develop biodegradable materials capable of capturing fine particulate matter (PM2.5) without compromising environmental sustainability. Polylactic acid (PLA) was used as the primary polymer, with the addition of SiO2 and MoS2 to enhance the fibers' charge retention and filtration performance. The fibers were charged electrostatically to improve particle capture efficiency. The experimental results showed that fibers containing 5% MoS2 exhibited the highest filtration efficiency, surpassing those with SiO2, despite MoS2 being a semiconductor and SiO2 a dielectric. Furthermore, the addition of MoS2 improved the filtration efficiency across a range of particle sizes (0.2-1 µm) while maintaining a manageable pressure drop. These findings suggest that incorporating MoS2 in electret nonwoven structures can significantly improve filtration performance, making it a promising material for advanced air filtration applications. This study contributes to the development of eco-friendly filtration materials with high performance, essential in reducing exposure to airborne pollutants.

Environmental risks of mask wastes binding pollutants: Phytotoxicity, microbial community, nitrogen and carbon cycles

The increasing contamination of mask wastes presents a significant global challenge to ecological health. However, there is a lack of comprehensive understanding regarding the environmental risks that mask wastes pose to soil. In this study, a total of 12 mask wastes were collected from landfills. Mask wastes exhibited negligible morphological changes, and bound eight metals and four types of organic pollutants. Masks combined with pollutants inhibited the growth of alfalfa and Elymus nutans, reducing underground biomass by 84.6 %. Mask wastes decreased the Chao1 index and the relative abundances (RAs) of functional bacteria (Micrococcales, Gemmatimonadales, and Sphingomonadales). Metagenomic analysis showed that mask wastes diminished the RAs of functional genes associated with nitrification (amoABC and HAO), denitrification (nirKS and nosZ), glycolysis (gap2), and TCA cycle (aclAB and mdh), thereby inhibiting the nitrogen transformation and ATP production. Furthermore, some pathogenic viruses (Herpesviridae and Tunggulvirus) were also found on the mask wastes. Structural equation models demonstrated that mask wastes restrained soil enzyme activities, ultimately affecting nitrogen and carbon cycles. Collectively, these evidences indicate that mask wastes contribute to soil health and metabolic function disturbances. This study offers a new perspective on the potential environmental risks associated with the improper disposal of masks.

Multifunctional FFP2 Face Mask for White Light Disinfection and Pathogens Detection using Hybrid Nanostructures and Optical Metasurfaces

A new generation of an FFP2 (Filtering Face Piece of type 2) smart face mask is achieved by integrating broadband hybrid nanomaterials and a self-assembled optical metasurface. The multifunctional FFP2 face mask shows simultaneously white light-assisted on-demand disinfection properties and versatile biosensing capabilities. These properties are achieved by a powerful combination of white light thermoplasmonic responsive hybrid nanomaterials, which provide excellent photo-thermal disinfection properties, and optical metasurface-based colorimetric biosensors, with a very low limit of pathogens detection. The realized system is studied in optical, morphological, spectroscopic, and cell viability assay experiments and environmental monitoring of harmful pathogens, thus highlighting the extraordinary properties in reusability and pathogens detection of the innovative face mask.

Masks and respirators for prevention of respiratory infections: a state of the science review

SUMMARYThis narrative review and meta-analysis summarizes a broad evidence base on the benefits-and also the practicalities, disbenefits, harms and personal, sociocultural and environmental impacts-of masks and masking. Our synthesis of evidence from over 100 published reviews and selected primary studies, including re-analyzing contested meta-analyses of key clinical trials, produced seven key findings. First, there is strong and consistent evidence for airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory pathogens. Second, masks are, if correctly and consistently worn, effective in reducing transmission of respiratory diseases and show a dose-response effect. Third, respirators are significantly more effective than medical or cloth masks. Fourth, mask mandates are, overall, effective in reducing community transmission of respiratory pathogens. Fifth, masks are important sociocultural symbols; non-adherence to masking is sometimes linked to political and ideological beliefs and to widely circulated mis- or disinformation. Sixth, while there is much evidence that masks are not generally harmful to the general population, masking may be relatively contraindicated in individuals with certain medical conditions, who may require exemption. Furthermore, certain groups (notably D/deaf people) are disadvantaged when others are masked. Finally, there are risks to the environment from single-use masks and respirators. We propose an agenda for future research, including improved characterization of the situations in which masking should be recommended or mandated; attention to comfort and acceptability; generalized and disability-focused communication support in settings where masks are worn; and development and testing of novel materials and designs for improved filtration, breathability, and environmental impact.

Microplastics from face mask impairs sperm motility

The COVID-19 pandemic has resulted in unprecedented plastic pollution from single-used personal protective equipment (PPE), especially face masks, in coastal and marine environments. The secondary pollutants, microplastics from face masks (mask MP), rise concern about their detrimental effects on marine organisms, terrestrial organisms and even human. Using a mouse model, oral exposure to mask MP at two doses, 0.1 and 1 mg MP/day for 21 days, caused no change in animal locomotion, total weight, or sperm counts, but caused damage to sperm motility with increased curvilinear velocity (VCL). The high-dose mask MP exposure caused a significant decrease in linearity (LIN) of sperm motility. Further testicular transcriptomic analysis revealed perturbed pathways related to spermatogenesis, oxidative stress, inflammation, metabolism and energy production. Collectively, our findings substantiate that microplastics from face masks yield adverse effects on mammalian reproductive capacity, highlighting the need for improved plastic waste management and development of environmentally friendly materials.

Purine-Doped g-C3N4-Modified Fabrics for Personal Protective Masks with Rapid and Sustained Antibacterial Activity

Protective masks are critical to impeding microorganism transmission but can propagate infection via pathogen buildup and face touching. To reduce this liability, we integrated electrospun photocatalytic graphitic carbon nitride (g-C3N4) nanoflakes into standard surgical masks to confer a self-sanitization capacity. By optimizing the purine/melamine precursor ratio during synthesis, we reduced the g-C3N4 band gap from 2.92 to 2.05 eV, eliciting a 4× increase in sterilizing hydrogen peroxide production under visible light. This narrower band gap enables robust photocatalytic generation of reactive oxygen species from environmental and breath humidity to swiftly eliminate accumulated microbes. Under ambient sunlight, the g-C3N4 nanocomposite mask layer achieved a 97% reduction in the bacterial viability during typical use. Because the optimized band gap also allows photocatalytic activity under shadowless lamp illumination, the self-cleaning functionality could mitigate infection risk from residual pathogens in routine hospital settings. Both g-C3N4 and polycaprolactone demonstrate favorable biocompatibility and biodegradability, making this approach preferable over current commercially available metal-based options. Given the abundance and low cost of these components, this scalable approach could expand global access to reusable self-sanitizing protective masks, serving as a sustainable public health preparedness measure against future pandemics, especially in resource-limited settings.

Microplastics release from face masks: Characteristics, influential factors, and potential risks

Since the COVID-19 pandemic, face masks have been used popularly and disposed of improperly, leading to the generation of a large amount of microplastics. The objective of this review is to provide a comprehensive insight into the characteristics of mask-derived microplastics, the influential factors of microplastics release, and the potential risks of these microplastics to the environment and organisms. Mask-derived microplastics were predominantly transparent fibers, with a length of <1 mm. The release of microplastics from masks is mainly influenced by mask types, use habits, and weathering conditions. Under the same conditions, surgical masks release more microplastics than other types of masks. Long-term wearing of masks and the disinfection for reuse can promote the release of microplastics. Environmental media, UV irradiation, temperature, pH value, and mechanical shear can also influence the microplastics release. The risks of mask-derived microplastics to human health via inhalation cannot be neglected. Future studies should pay more attention to the release of microplastics from the masks with alternative materials and under more weathering conditions.

Assessment of inhalation exposure to microplastic particles when disposable masks are repeatedly used

Wearing masks to prevent infectious diseases, especially during the COVID-19 pandemic, is common. However, concerns arise about inhalation exposure to microplastics (MPs) when disposable masks are improperly reused. In this study, we assessed whether disposable masks release inhalable MPs when reused in simulated wearing conditions. All experiments were conducted using a controlled test chamber setup with a constant inspiratory flow. Commercially available medical masks with a three-layer material, composition comprising polypropylene (PP in the outer and middle layers) and polyethylene (PE in the inner layer), were used as the test material. Brand-new masks with and without hand rubbing, as well as reused medical masks, were tested. Physical properties (number, size, and shape) and chemical composition (polymers) were identified using various analytical techniques such as fluorescence staining, fluorescence microscopy, and micro-Fourier Transform Infrared Spectroscopy (μFTIR). Scanning Electron Microscopy (SEM) was used to scrutinize the surface structure of reused masks across different layers, elucidating the mechanism behind the MP generation. The findings revealed that brand-new masks subjected to hand rubbing exhibited a higher cumulative count of MPs, averaging approximately 1.5 times more than those without hand rubbing. Fragments remained the predominant shape across all selected size classes among the released MPs from reused masks, primarily through a physical abrasion mechanism, accounting for >90 % of the total MPs. The numbers of PE particles were higher than PP particles, indicating that the inner layer of the mask contributed more inhalable MPs than the middle and outer layers combined. The released MPs from reused masks reached their peak after 8 h of wearing. This implies that regularly replacing masks serves as a preventive measure and mitigates associated health risks of inhalation exposure to MPs.

All-inorganic lead halide perovskites for photocatalysis: a review

Nowadays, environmental pollution and the energy crisis are two significant concerns in the world, and photocatalysis is seen as a key solution to these issues. All-inorganic lead halide perovskites have been extensively utilized in photocatalysis and have become one of the most promising materials in recent years. The superior performance of all-inorganic lead halide perovskites distinguish them from other photocatalysts. Since pure lead halide perovskites typically have shortcomings, such as low stability, poor active sites, and ineffective carrier extraction, that restrict their use in photocatalytic reactions, it is crucial to enhance their photocatalytic activity and stability. Huge progress has been made to deal with these critical issues to enhance the effects of all-inorganic lead halide perovskites as efficient photocatalysts in a wide range of applications. In this manuscript, the synthesis methods of all-inorganic lead halide perovskites are discussed, and promising strategies are proposed for superior photocatalytic performance. Moreover, the research progress of photocatalysis applications are summarized; finally, the issues of all-inorganic lead halide perovskite photocatalytic materials at the current state and future research directions are also analyzed and discussed. We hope that this manuscript will provide novel insights to researchers to further promote the research on photocatalysis based on all-inorganic lead halide perovskites.

Impacts of climate change on the fate of contaminants through extreme weather events

The direct impacts of climate change involve a multitude of phenomena, including rising sea levels, intensified severe weather events such as droughts and flooding, increased temperatures leading to wildfires, and unpredictable fluctuations in rainfall. This comprehensive review intends to examine firstly the probable consequences of climate change on extreme weather events such as drought, flood and wildfire. This review subsequently examines the release and transformation of contaminants in terrestrial, aquatic, and atmospheric environments in response to extreme weather events driven by climate change. While drought and flood influence the dynamics of inorganic and organic contaminants in terrestrial and aquatic environments, thereby influencing their mobility and transport, wildfire results in the release and spread of organic contaminants in the atmosphere. There is a nascent awareness of climate change's influence of climate change-induced extreme weather events on the dynamics of environmental contaminants in the scientific community and decision-making processes. The remediation industry, in particular, lags behind in adopting adaptive measures for managing contaminated environments affected by climate change-induced extreme weather events. However, recognizing the need for assessment measures represents a pivotal first step towards fostering more adaptive practices in the management of contaminated environments. We highlight the urgency of collaboration between environmental chemists and climate change experts, emphasizing the importance of jointly assessing the fate of contaminants and rigorous action to augment risk assessment and remediation strategies to safeguard the health of our environment.

Personal protective equipment (PPE) pollution associated with the COVID-19 pandemic on beaches in the eastern region of the Gulf of California, Mexico

The COVID-19 pandemic has led to an increase in plastic pollution, including improper disposal of personal protective equipment (PPE). This study focuses on examining the presence and distribution of discarded PPE in three locations in Sonora, Mexico, located within the Gulf of California. Transects were conducted in 2021 and 2022, during which PPE items were visually identified, photographed, and classified. Face masks were found to be the most prevalent PPE type (96% of the total), with polymer-based masks being the most commonly observed (97% of the total). The density of PPE was higher on recreational beaches compared to non-recreational ones. Statistical analysis revealed a significant difference (W = 217.5, p = 0.014) in the PPE density between the sampled recreational beaches in 2021 and 2022, with a higher density recorded in the first year. Improper disposal of PPE poses environmental risks and potential threats to marine organisms. The documented discarded COVID-19-related PPE in this study provides important baseline information for future research and monitoring. This information is valuable to better understand the ecotoxicological effects of PPE and develop effective waste management strategies in the Gulf of California.

Utilization of Waste Natural Fibers Mixed with Polylactic Acid (PLA) Bicomponent Fiber: Incorporating Kapok and Cattail Fibers for Nonwoven Medical Textile Applications

Disposable surgical gowns are usually made from petroleum-based synthetic fibers that do not naturally decompose, impacting the environment. A promising approach to diminish the environmental impact of disposable gowns involves utilizing natural fibers and/or bio-based synthetic fibers. In this study, composite webs from polylactic acid (PLA) bicomponent fiber and natural fibers, cattail and kapok fibers, were prepared using the hot press method. Only the sheath region of the PLA bicomponent fiber melted, acting as an adhesive that enhanced the strength and reduced the thickness of the composite web compared with its state before hot pressing. The mechanical and physical properties of these composite webs were evaluated. Composite webs created from kapok fibers displayed a creamy yellowish-white color, while those made from cattail fibers showed a light yellowish-brown color. Additionally, the addition of natural fibers endowed the composite webs with hydrophobic properties. The maximum natural fiber content, at a ratio of 30:70 (natural fiber to PLA fiber), can be incorporated while maintaining proper water vapor permeability and mechanical properties. This nonwoven material presents an alternative with the potential to replace petroleum-based surgical gowns.

Advantages and disadvantages of maintaining the mandatory use of masks in health centers and nursing homes in Spain. How and when is it justified to maintain it?

We address the advantages and disadvantages of maintaining the mandatory use of masks in health centers and nursing homes in the current epidemiological situation in Spain and after the declaration of the World Health Organization on May 5, 2023 of the end of COVID-19 as public health emergency. We advocate for prudence and flexibility, respecting the individual decision to wear a mask and emphasizing the need for its use when symptoms suggestive of a respiratory infection appear, in situations of special vulnerability (such as immunosuppression), or when caring for patients with those infections. At present, given the observed low risk of severe COVID-19 and the low transmission of other respiratory infections, we believe that it is disproportionate to maintain the mandatory use of masks in a general way in health centers and nursing homes. However, this could change depending on the results of epidemiological surveillance and it would be necessary to reconsider returning to the obligation in periods with a high incidence of respiratory infections.