Bacterial Aerosol in Ambient Air—A Review Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript deals with a very relevant and timely topic and focuses on the importance of bacterial aerosols in the air and their impact on human health. The topic is well chosen and crucial to advance our understanding of bioaerosols in relation to air quality and public health. I think the publication can be improved by adding and arranging tables and photos.

The existing table in the paper provides a wealth of data, but could benefit from clearer organization and formatting. The data in the table is very dense and extensive. Consider simplifying the tables by adding several new tables from the existing table. Table for particulate matter, temperature, ozone...

The manuscript would benefit greatly from the inclusion of more graphical elements such as graphs, diagrams or flow charts to visually represent the complex interactions between bacterial aerosols, pollutants and meteorological factors. Graphical summaries of key results from the tables could help to make the data more accessible and interesting to the reader.

The visual presentation of the data needs to be improved with better tables, and the inclusion of relevant charts or graphs would greatly enhance the readability and impact of the manuscript. These changes will not only facilitate the understanding and interpretation of the data presented in the paper.

Comments on the Quality of English Language

English is at a satisfactory level

Author Response

Manuscript ID applsci-3172326 – minor revisions

Detailed answers to:

Reviewer #1

General Comment: The manuscript deals with a very relevant and timely topic and focuses on the importance of bacterial aerosols in the air and their impact on human health. The topic is well chosen and crucial to advance our understanding of bioaerosols in relation to air quality and public health. I think the publication can be improved by adding and arranging tables and photos.

The existing table in the paper provides a wealth of data, but could benefit from clearer organization and formatting. The data in the table is very dense and extensive. Consider simplifying the tables by adding several new tables from the existing table. Table for particulate matter, temperature, ozone...

The manuscript would benefit greatly from the inclusion of more graphical elements such as graphs, diagrams or flow charts to visually represent the complex interactions between bacterial aerosols, pollutants and meteorological factors. Graphical summaries of key results from the tables could help to make the data more accessible and interesting to the reader.

The visual presentation of the data needs to be improved with better tables, and the inclusion of relevant charts or graphs would greatly enhance the readability and impact of the manuscript. These changes will not only facilitate the understanding and interpretation of the data presented in the paper.

Answer and Action: Thank you for your thoughtful feedback.

We have carefully considered your suggestions and incorporated them into both the main text and the Supplementary Materials. We trust that these revisions will enhance the clarity and presentation of the manuscript, and we hope they will meet your approval.

Once again, we would like to express our appreciation for the efforts and helpful comments. Enclosed please find the revised version of our paper.

Yours sincerely,

Ewa Brągoszewska and Anna Mainka

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript prepared by Brągoszewska et al. titled “Bacterial aerosol in ambient air – a review study” examines the impact of airborne bacteria, a key component of bioaerosols, on ambient air quality and their implications for human health. The paper highlights the variability in bacterial levels across environments and seasons, driven by factors such as temperature, humidity, wind speed, and pollution, and emphasizes the need for further research to improve health risk assessments. The findings offer valuable insights for enhancing public health and environmental management. The paper is informative, well-structured, and highly relevant to the journal’s scope. However, the manuscript would benefit from improvements in writing, particularly in addressing the grammatical issues. Additionally, there are some inconsistencies between the conclusions and the supporting evidence. I recommend that the authors carefully review and verify all statements to ensure accuracy and coherence. I recommend this manuscript for publication pending minor revisions.

Specific comments:

1.     Line 51: Please add “per day”.

2.     Lines 195-198: Your statement suggests that increased concentrations of PM2.5 in winter lead to a rise in bioaerosols; however, the observations indicate a negative correlation, which appears contradictory.

3.     Line 254: I recommend removing “while the concentrations of bacteria,”

4.     Lines 298-300: The sentence should be “… suggesting that bacterial levels may decrease despite lower temperatures.”

5.     Lines 307-308: “reported by Kowalski et al., …”

6.     Line 411: You might want to remove “Propagative role of rain”.

7.     Lines 412-413: There seems to be some missing information in this sentence.

8.     Section 4: In the fields you have proposed, are there any recent studies or existing work that present preliminary results? If such work exists, it would be valuable to briefly discuss these pioneering efforts to provide context and demonstrate how your proposed research builds on or differs from these initial findings.

9.  Lines 428-440: I find this paragraph difficult to understand. I recommend rewriting this section for clarity. Alternatively, you might consider splitting it into two separate sections: one focusing on predictive models and the other on the characterization of bioaerosol components.

Comments on the Quality of English Language

There are lots of grammar issues throughout the manuscript that need to be addressed. For example, specific issues can be found on lines 231-232, lines 278-279, and lines 283-285. I recommend a thorough review of the entire manuscript to correct these and any other grammatical errors.

Author Response

Manuscript ID applsci-3172326 – minor revisions

Detailed answers to:

Reviewer #2

General Comment:

The manuscript prepared by Brągoszewska et al. titled “Bacterial aerosol in ambient air – a review study” examines the impact of airborne bacteria, a key component of bioaerosols, on ambient air quality and their implications for human health. The paper highlights the variability in bacterial levels across environments and seasons, driven by factors such as temperature, humidity, wind speed, and pollution, and emphasizes the need for further research to improve health risk assessments. The findings offer valuable insights for enhancing public health and environmental management. The paper is informative, well-structured, and highly relevant to the journal’s scope. However, the manuscript would benefit from improvements in writing, particularly in addressing the grammatical issues. Additionally, there are some inconsistencies between the conclusions and the supporting evidence. I recommend that the authors carefully review and verify all statements to ensure accuracy and coherence. I recommend this manuscript for publication pending minor revisions.

Answer and Action: Thank you for your thoughtful feedback.

We have carefully considered your suggestions and incorporated them into both the main text. We trust that these revisions will enhance the clarity and presentation of the manuscript, and we hope they will meet your approval.

Comment 1: Line 51: Please add “per day”.

Answer: It has been corrected.

Comment 2: Lines 195-198: Your statement suggests that increased concentrations of PM2.5 in winter lead to a rise in bioaerosols; however, the observations indicate a negative correlation, which appears contradictory.

Answer: We have added the following sentences to the main text:

However, their observations did not identify a statistically significant positive corre-lation between PM2.5 and bioaerosol levels during this season. This suggests that, although higher PM2.5 levels in winter may be associated with factors that could po-tentially influence bioaerosol concentrations, the data do not support a significant increase in bioaerosols.

Comment 3: Line 254: I recommend removing “while the concentrations of bacteria,”

Answer: We have removed the phrase “while the concentrations of bacteria” as recommended. The sentence has been corrected accordingly in the main text.

Comment 4: Lines 298-300: The sentence should be “… suggesting that bacterial levels may decrease despite lower temperatures.”

Answer: Thank you for your comment. We have revised the sentence as suggested, replacing "decrease" with "increase".

Comment 5: Lines 307-308: “reported by Kowalski et al., …”

Answer: The phrase "reported by Kowalski et al." has been included.

Comment 6: Line 411: You might want to remove “Propagative role of rain”.

Answer: It has been removed from the main text.

Comment 7: Lines 412-413: There seems to be some missing information in this sentence.

Answer: Thank you for pointing this out. The issue with lines 412-413 resulted from an earlier error on our part. This has now been corrected, and the sentence should be accurate:

The question of why bacterial aerosol concentrations may either increase or decrease during rain events remains unresolved.

Comment 8: Section 4: In the fields you have proposed, are there any recent studies or existing work that present preliminary results? If such work exists, it would be valuable to briefly discuss these pioneering efforts to provide context and demonstrate how your proposed research builds on or differs from these initial findings.

Answer: Thank you for your valuable feedback on Section 4.

We appreciate your suggestion to discuss recent studies or preliminary results in the proposed fields. We added information about research performed by Raisi et al, and Kallawicha et. al., additionally mentioned other reviews pointing on future directions:

For example, Raisi [72] observed that bacterial concentrations were positively correlated with relative humidity and fungal concentrations, and negatively correlated with solar radiation. Similarly, Kallawicha et al. [32] identified temperature, relative humidity, and particulate matter as the primary predictors of ambient bacteria and endotoxins in their regression model, which aligns with the findings of our literature review. Other reviews [11,99] emphasize the need for future studies to include additional variables to better understand the relationships between bacterial exposure and adverse health outcomes, particularly during rainstorms.

We also added references pointing out gaps in the current literature. We would like to clarify that the purpose of the "Future Directions" section is to identify critical gaps in current knowledge and highlight areas where further research is needed. This section aims to outline the necessary research directions rather than providing a comprehensive review of existing studies or preliminary findings. Although there are studies related to bioaerosols that offer preliminary insights, they do not directly address the specific focus of our proposed research. By identifying these knowledge gaps, we believe our research will offer new perspectives and significantly contribute to advancing our understanding of the impacts of bioaerosols on climate, health, and ecosystems.

We hope that our "Future Directions" section will be valuable in guiding future research efforts.

Comment 9: Lines 428-440: I find this paragraph difficult to understand. I recommend rewriting this section for clarity. Alternatively, you might consider splitting it into two separate sections: one focusing on predictive models and the other on the characterization of bioaerosol components.

Answer: We have rewritten this section to enhance clarity. We hope these changes address your concerns and improve the readability of the manuscript.

Significant progress has been made in developing predictive models for ambient bacteria and endotoxins, though further refinement is required. For example, Raisi [72] observed that bacterial concentrations were positively correlated with relative humidity and fungal concentrations, and negatively correlated with solar radiation. Similarly, Kallawicha et al. [32] identified temperature, relative humidity, and particulate matter as the primary predictors of ambient bacteria and endotoxins in their regression model, which aligns with the findings of our literature review. Other reviews [11,99] emphasize the need for future studies to include additional variables to better understand the relationships between bacterial exposure and adverse health outcomes, particularly during rainstorms. Despite advancements in molecular methods, current exposure limits for biological aerosols still primarily rely on traditional culturable and microscopic techniques due to their simplicity and cost-effectiveness. To address this gap, research should focus on the detailed characterization of bioaerosol components using advanced technologies such as next-generation sequencing (NGS) and fluorescence detection. This approach will facilitate the development of comprehensive guidelines for acceptable exposure standards, which are currently lacking but are essential for improving risk assessment and public health protection.

Comment 10: There are lots of grammar issues throughout the manuscript that need to be addressed. For example, specific issues can be found on lines 231-232, lines 278-279, and lines 283-285. I recommend a thorough review of the entire manuscript to correct these and any other grammatical errors.

Answer: Thank you for highlighting the grammatical issues in the manuscript. We have conducted a thorough review and made necessary corrections to improve the text. If any additional revisions are required, we will follow the Editor's guidance.

We appreciate your feedback and hope that these changes enhance the clarity and quality of the manuscript.

Once again, we would like to express our appreciation for the efforts and helpful comments. Enclosed please find the revised version of our paper.

Yours sincerely,

Ewa Brągoszewska and Anna Mainka