Comparative Analysis of Face Mask Usage and Environmental Impact in Asian Cities during and after the COVID-19 Pandemic
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Comparative Analysis of Face Mask Usage and Environmental Impact in Asian Cities during and after the COVID-19 Pandemic
The work presented in this paper is needed by those involved in the field, and therefore, should be shared with the society. However, the paper should be accepted for publication pending some modifications:
1. Although the authors provide an acceptable literature review on the environmental impact of masks, the section still lacks results from previous published work. It would be very useful to substantiate this section with more results from previous work.
2. Please provide the impact of microplastics from masks on humans in the "Introduction" section.
3. Are there any reasons other than income level for the selection of cities? If yes, please state the reason.
4. In Table S1, the authors have used Wikipedia as a source for some information. Wikipedia is not a trustworthy source and the authors should replace this source with a more appropriate and trustworthy source.
5. Line 217 “Table 1. Lee, Ajaj, and Luo”, this needs to be written as Lee at al [add the reference number]. Also add the reference number for Schmutzet et al. in line 220 […].
6. References must be carefully cited. Authors should pay careful attention to consistency of citation.
7. The authors stated that “gender and education level” were significant influencing factors for the use of cloth face masks, with both showing a positive correlation. I agree that education level is perhaps the most important factor. However, gender does not seem to me to be very important compared to education level. Could the authors explore the published literature in more detail and provide a few sentences on this regards?
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 1 Comments
Point 1: Although the authors provide an acceptable literature review on the environmental impact of masks, the section still lacks results from previous published work. It would be very useful to substantiate this section with more results from previous work.
Response 1: Thank you very much for your suggestion. We have taken it into consideration and have added more results from previously published work to substantiate the literature review section on the environmental impact of masks. We hope this enhancement strengthens the overall content and value of our manuscript. In response to this suggestion, we have made the following changes in the article.
(P.3 L.107-120)
“2.3. Adverse health effects in humans and animals
The utilization of face masks has resulted in the contamination of ecosystems with microplastics, which has consequently led to human exposure through potential pathways such as ingestion, inhalation and dermal contact [9]. Microplastic particles generated from discarded face masks also have the potential to enter the food chain, thereby posing risks to both aquatic and terrestrial organisms [9-11]. In aquatic ecosystems, microplastics are ingested by aquatic animals, which can result in adverse effects on their growth and development, as well as the transfer of nutrients to higher organisms in the food chain [20]. The presence of microplastics has been demonstrated to exert a considerable influence on the biology of amphibians and reptiles [21]. In soil environments, microplastics are a common pollutant, particularly aged PE (polyethylene) microplastics, which can damage the intestinal structure and function of soil organisms like earthworms, leading to oxidative damage within their bodies [22]. Furthermore, discarded masks may be ingested by terrestrial animals, which could result in mortality, contamination of food chains, and ecological imbalances [23].”
Point 2: Please provide the impact of microplastics from masks on humans in the "Introduction" section.
Response 2: Thank you for your opinion. In response to this suggestion, we have made the following changes in the article. (P.3 L.39-43)
“ The potential hazards of microplastics to human health are manifested in toxic chemical components, pathways for contaminants, and physical harm [9], and composting household waste will introduce microplastics into the agro-ecosystem, enter the human body through the food chain, and affect human health [10,11].”
Point 3: Are there any reasons other than income level for the selection of cities? If yes, please state the reason.
Response 3:
Yes, we added some additional text to address this question, as below. (P.4 L.172-176)
“In addition to income level, the selection of cities was influenced by our partnership with ERIA and the Regional Knowledge Centre for Marine Plastic Debris (RKC-MPD). These cities were chosen because they offer the potential for conducting in-depth re-search due to established collaborations and access to necessary data, making them suitable candidates for this study.”
Point 4: In Table S1, the authors have used Wikipedia as a source for some information. Wikipedia is not a trustworthy source and the authors should replace this source with a more appropriate and trustworthy source.
Response 4: As you suggested, we have replaced this source with an official local data source: “Badan Pusat Statistik Jawa Barat (2022). Produk Domestik Regional Bruto Kabupaten/kota di Jawa Barat 2019-2021. Bandung: Badan Pusat Statistik.”
Point 5: Line 217 “Table 1. Lee, Ajaj, and Luo”, this needs to be written as Lee at al [add the reference number]. Also add the reference number for Schmutzet et al. in line 220 […].
Response 5: Thank you very much for your thorough review and valuable suggestions. We have taken your comments seriously and made the corresponding revisions to our manuscript as follows (P.6 L.244-252)
“Environmental impact intensity indicators for each type of mask were collected from relevant literature, integrated, and summarized in Table 1. Lee et al. [17], Ajaj et al. [38], and Luo et al. [46] estimated the lifecycle carbon footprint of different mask types using a one-month reference period. As a result, the carbon footprint for single-use masks was set at 0.018-0.043 kgCO2eq per piece. Cloth masks had carbon footprints of 0.23-0.571 kgCO2eq [17,38,41,46]. Additionally, Schmutz et al. [41] estimated the lifecycle water footprint of single-use masks and cloth masks as 0.07 m3H2Oeq and 0.35 m3H2Oeq, respectively, using a one-week reference period. The measured weights for each type of mask were 2.88 g (single-use) and 11.78 g (cloth) respectively [41].”
Point 6: References must be carefully cited. Authors should pay careful attention to consistency of citation.
Response 6: Thank you very much for your suggestion. This was a good reminder to increase our vigilance when authors from different institutions are using different citation management software. We have carefully reviewed and corrected the in-text citations and references.
Point 7: The authors stated that “gender and education level” were significant influencing factors for the use of cloth face masks, with both showing a positive correlation. I agree that education level is perhaps the most important factor. However, gender does not seem to me to be very important compared to education level. Could the authors explore the published literature in more detail and provide a few sentences on this regards?
Response 7: Thank you for your opinion. We agree that the larger literature may suggest a different weighting for education and gender in some circumstances. That said, in our survey the data gave a strong indication that gender was indeed a particularly strong influence / predictor of behavior related to masks. Comparative work on cross-cultural mask use behavior may reveal other social influences that inflate or suppress gender-based mask use; however, we have not seen this research to date. This indicates room for further research to help tease out the varied influences on behavior. For example, it may be the case that the strong signal from gender we observe here is conflating stronger female achievement in education. Similarly, strong socio-cultural influences may be at play that put emphasis on certain types of behavior as being more feminine or less masculine, thus influencing risk-taking behavior (or the perception of risk).
So, our conclusions in this paper are based more strictly on the results of our own survey, which indicate a significant correlation of gender with increased use of single-use masks in three out of the five sampled cities. All of the influencing factors, including educational achievement, showed varying degrees of strength in the five cities (for detailed specifics, please refer to section 4.4).
Thank you again for your positive and constructive comments and suggestions on our manuscript. We have tried our best to improve the manuscript and made some changes in manuscript. We appreciate for your warm work earnestly, and really hope that the correction will meet with approval.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe work, based on questionnaire surveys conducted in five cities (Shanghai, Harbin, Hanoi, Phnom Penh, and Depok) across Asia, analyzed the usage patterns of single-use and cloth face masks during different periods of the COVID-19 pandemic, including before, during, and post-pandemic phases. Additionally, the study examined individual characteristics influencing mask usage patterns and estimated the environmental impact of mask usage. Results reveal that the outbreak of COVID-19 led to a significant increase in the usage of single-use face masks, with a five-fold increase observed during the pandemic. Although there was a decline in usage during the transition to the 'new normal' phase, mask usage remained three times higher than pre-pandemic levels. Furthermore, mask usage patterns were influenced not only by demographic factors such as age, gender, and education level but also by regional characteristics including air quality and commuting habits. The observed trends underscore the complex interplay between public health priorities and environmental considerations. Recommendations from the study include the promotion of sustainable mask-wearing practices, such as the adoption of reusable options and the implementation of proper disposal methods. The habituation of mask-wearing is influenced by various factors, including the pandemic’s progression, other infectious diseases, climate change, and lifestyle habits. Further tracking of mask usage patterns and understanding the multifaceted factors shaping these trends are crucial. By integrating insights from both public health and environmental perspectives, policymakers and stakeholders can develop effective strategies to address current and future challenges related to mask usage, thereby safeguarding human health and the environment.
This is very valuable work. It could be published after minor revision as below.
General Remarks
Point 5 and 6 have the same title “Conclusions”. It should be changed.
Detailed remarks
1. Figure 1-4 should be self-explaining. Please add proper information.
Table 2 should be self-explaining. Please add proper information.
Author Response
Response to Reviewer 2 Comments
Point 1: Figure 1-4 should be self-explaining. Please add proper information. Table 2 should be self-explaining. Please add proper information.
Response 1: Thank you very much for your suggestion. We have ensured that Figures 1-4 and Table 2 are self-explaining by adding proper captions and/or explanatory notes to provide necessary context and information. We appreciate the opportunity to enhance the clarity and accessibility of our paper
Thank you again for your positive and constructive comments and suggestions on our manuscript. We have tried our best to improve the manuscript and made some changes in manuscript. We appreciate for your warm work earnestly, and really hope that the correction will meet with approval.
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsThe article "Comparative Analysis of Face Mask Usage and Environmental Impact in Asian Cities during and after the COVID-19 Pandemic" is well-prepared and an interesting material for publication in Sustainability.I recommend a minor revision according to the comments below.
1. In general, the introduction should emphasize the importance and main specific goal of the research.
2. 2. 3.3.2. Type of masks: it would be useful to add photos or drawings of the masks tested
3. Figure 2:The drawing is illegible, please enlarge it to make the legend visible.
4. 4.4. Comprehensive impact of respondent characteristics on mask usage: This section requires more discussion and a clearer summary.
5. Conclusion:Please list the main conclusions because it is not very clear.
Comments on the Quality of English Language
Minor editing of English language required
Author Response
Response to Reviewer 3 Comments
Point 1: In general, the introduction should emphasize the importance and main specific goal of the research.
Response 1: Thank you for your attention to detail and suggestions for improvement. We have updated the manuscript as requested. The purpose of the article is to emphasize that maintaining a focus on sustainable development while meeting humanity's mask needs is critically important. While pursuing health and safety, it is essential to recognize the significance of adopting sustainable approaches to mask usage and management in order to minimize adverse environmental impacts and safeguard the interests of future generations. Key to these efforts will be understanding the influences on mask wearing and disposal behaviors so that adequate policies can be developed and infrastructure put in place.
Point 2: 2. 3.3.2. Type of masks: it would be useful to add photos or drawings of the masks tested.
Response 2: Thank you for your valuable feedback. We have added images of the two types of masks, as shown in Figure 2.
Figure 2. Single-use surgical face mask and Reusable face mask (Cloth face mask)
Point 3: Figure 2: The drawing is illegible, please enlarge it to make the legend visible.
Response 3: We appreciate your valuable feedback and have made the necessary adjustments to Figure 3. We have enlarged the size of the figure to ensure that the legend is now clearly visible, enhancing the readability and information clarity of the chart. We are committed to delivering work that meets the highest standards of clarity and detail, and we hope that this revision addresses your concern.
Point 4: 4.4. Comprehensive impact of respondent characteristics on mask usage: This section requires more discussion and a clearer summary.
Response 4: Thank you very much for your suggestion. We have expanded the section to more clearly and deeply discuss the influences of the measured characteristics on mask use. We discuss the different situations in various regions, including where different measured characteristics are demonstrating higher or lower influence in different locations. Some conclusions are drawn from these observations, which are discussed further in the Discussion section.
Point 5: Conclusion: Please list the main conclusions because it is not very clear.
Response 5: Thank you very much for your suggestion. We have added a more structured opening to this section, including a paragraph more plainly stating the conclusions:
“Our findings reveal that the outbreak of COVID-19 led to a significant increase in the usage of single-use face masks across all five sample cities, with a five-fold increase observed during the pandemic. Although there was a decline in usage during the transition to the 'new normal' phase, mask usage remained three times higher than pre-pandemic levels. Furthermore, mask usage patterns were influenced not only by demographic factors such as age, gender, and education level but also by regional characteristics including air quality and commuting habits.”
Thank you again for your positive and constructive comments and suggestions on our manuscript. We have tried our best to improve the manuscript and made some changes in manuscript. We appreciate for your warm work earnestly, and really hope that the correction will meet with approval.
Author Response File: Author Response.docx
