The Emission Characteristics of VOCs and Environmental Health Risk Assessment in the Plywood Manufacturing Industry: A Case Study in Shandong Province
, Xin Zhang 1,4,* and Qingzhu Zhang 1Round 1
Reviewer 1 Report (Previous Reviewer 1)
Comments and Suggestions for AuthorsThe manuscript is original and represents a contribution to scientific knowledge.
Author Response
Comments: The manuscript is original and represents a contribution to scientific knowledge.
Response: Thanks for the recognition of this work.
Reviewer 2 Report (Previous Reviewer 2)
Comments and Suggestions for AuthorsThe article is devoted to current topics on sustainable development of industrial territories. A large amount of experimental material has been collected on the formation of volatile compounds and their effect on the health of workers at plywood enterprises. However, before publishing the material, for convenience and expanding the area of readers, it is necessary to eliminate some comments.
Comments:
1. In the introduction, please explain the scientific significance of the work. When using formaldehyde in adhesive coatings, it is logical that it will have the maximum concentration in the emissions. Why is there a need for a detailed study of the composition of VOCs? How much impact can this have on changing treatment systems in the context of sustainable development?
2. In the tables and figures, the order in which substances are mentioned is different, which makes their analysis difficult. To more clearly interpret the data and highlight the most significant pollutants, please consider changing the order of mentioning VOCs during comparison and make it the same for borth enterprises.
3. In conclusion, it is advisable to give a more detailed answer to the question: How will the outcomes of this study enhance the understanding of VOCs emissions within the plywood manufacturing industry, if the data for two enterprises turned out to be contradictory?
Author Response
Comments 1: In the introduction, please explain the scientific significance of the work. When using formaldehyde in adhesive coatings, it is logical that it will have the maximum concentration in the emissions. Why is there a need for a detailed study of the composition of VOCs? How much impact can this have on changing treatment systems in the context of sustainable development?
Response 1: We have explained the significance of this work at the end of the introduction. The raw material used in the plywood manufacturing industry is urea-formaldehyde resin, and its main component is formaldehyde, so formaldehyde emissions are indeed the largest. However, the use of adhesives also inevitably involves the use of solvents, resulting in the emergence of other characteristic VOC species in addition to formaldehyde. It can be observed that the unorganized emissions in the adhesive-coating process of enterprise A and the unorganized emissions in the adhesive-coating and hot-pressing process of enterprise B have dichloromethane and methyl methacrylate as characteristic species. Dichloromethane and methyl methacrylate are the main components of solvents, indicating that in addition to formaldehyde, we should pay attention to the importance of VOC emissions in solvents in the future. In addition, in the process of manufacturing plywood, especially in the hot-pressing process, formaldehyde can also be converted into other OVOCs. For organized emissions, the exhaust gas has been purified by a photocatalytic device, and the specific VOC components will be further changed. To sum up, it is very necessary to study the specific VOC components emitted in the plywood manufacturing process, which can provide certain guidance for the targeted improvement of waste gas collection and treatment equipment.
Comments 2: In the tables and figures, the order in which substances are mentioned is different, which makes their analysis difficult. To more clearly interpret the data and highlight the most significant pollutants, please consider changing the order of mentioning VOCs during comparison and make it the same for both enterprises.
Response 2: We would like to further explain the sequence of substances in the tables and pictures. In Table S1, all VOC species analyzed in the study are listed, and all substances are classified and sorted in the order of alkanes, alkenes, alkynes, aromatics, halohydrocarbons, OVOCs, and VOSCs. The substances in Figures 2, 4, 5a, 6, and 7 are arranged in the same order as in Table S1. Since Figure 3 and Figure 5b involve the screening of the top ten or three substances respectively, they are listed in order from high to low. When using words to describe the results, the feature substances are ranked from highest to lowest, and the data is indicated after the substance for clear expression.
Comments 3: In conclusion, it is advisable to give a more detailed answer to the question: How will the outcomes of this study enhance the understanding of VOCs emissions within the plywood manufacturing industry, if the data for two enterprises turned out to be contradictory?
Response 3: Since the types of raw materials, production processes and waste gas treatment technology of the plywood manufacturing industry are fixed, this study selected two enterprises with different production scales for comprehensive analysis to obtain the VOC emission characteristics of this industry in Shandong Province. There is no contradiction between the data of the two companies in this study, and we believe that the relevant conclusions about the emission characteristics of VOCs are reasonable.
Round 2
Reviewer 2 Report (Previous Reviewer 2)
Comments and Suggestions for AuthorsDear authors, your comments have clarified issues related to the structure and presentation of data. Taking into account the corrections made, the article may be accepted for publication.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsControlling VOC emissions presents a significant challenge for the plywood manufacturing industry, in there are a number of manufacturing stages during which VOCs are emitted: for example, gluing, painting, laminating and varnishing. That means there may be several areas where workers are exposed to VOCs at different stages of the production process, such as paint booths and spray paint walls. Therefore, it is necessary to implement strategies to improve indoor air quality, which requires detailed knowledge of the polluting components and how their emissions evolve over time. The manuscript shows the calculation of emission factors (EFm), VOC sources profile calculation methoth, estimation of reactivity of ozone formation potential (OFP) and health risks assessment. However, it does not describe how was used statistically. The authors must describe whether they consider the emissions as: Point emissions or Diffuse emissions.
The graphics are of very poor quality and do not allow us to clearly see the results obtained in the study.
It is necessary to mention which are the strictest emission limit values (mg/m3) in the case of VOC emissions, exposure to environmental pollutants such as VOCs constitute a risk to the health of. Therefore, it is requested that the manuscript consider or clearly describe in the emission factors the health risks associated with the emission of VOCs, which derive from their volatile, fat-soluble and toxic properties.
Consider that the manuscript contributes new information to what already exists. However, we suggest that the authors address details on the following:
- Exposure routes (respiratory system).
- Toxicokinetics.
- Recommended exposure limits from International Organizations (IARC, WHO, NIOSH, OSHA).
Comments for author File: 
Comments.pdf
It is recommended that the English be thoroughly reviewed by the authors and proofread by a native speaker.
Author Response
Comments 1: Consider that the manuscript contributes new information to what already exists. However, we suggest that the authors address details on the following: Exposure routes (respiratory system)
Response 1: We only considered VOCs emitted from unorganized sources in the workshop area for the health risk assessment. Long-term exposure to workshop air with high-level VOC concentrations is harmful to human health. Of course, the human body ingests harmful VOCs in the air through the respiratory system, which threatens health. We have added this detail to the health risk assessment section.
Comments 2: Toxicokinetics and recommended exposure limits from International Organizations (IARC, WHO, NIOSH, OSHA).
Response 2: On the calculation of health risk assessment, the widely used health risk assessment methods of VOCs mainly include non-cancer risk and lifetime cancer risk methods developed by the Environmental Protection Agency of the United States (US EPA). This has also been used and published in relevant papers. We have introduced relevant formulas in detail in the method section and indicated the references. The values and sources of relevant parameters have been listed in detail in Table S4.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper is devoted to study the VOCs emissions within the plywood manufacturing industry and their potential health risks to workers in the plywood manufacturing industry in Shandong province. Organized and unorganized emissions at some stages of plywood manufacturing were studied in detail.
It was described in sufficient detail which volatile compounds and in what quantities are released at different stages of manufacturing and at different enterprises. However, some important issues were not considered, which, in my opinion, need to be considered before accepting the article for publication.
Major revision:
1. The question of the sources of emission of these volatile compounds has not been addressed. How does the composition of VOCs correlate with the composition of the raw materials used? Does the origin and species of trees used affect the VOCs emitted? The answers to these questions could also form the basis for the development of regulations for the assessment of VOCs in this type of manufacturing.
2. The article does not indicate what air purification measures are currently being used in the studied areas, how many employees and how much time do they spend in these conditions? If the air in the work area is not being cleaned now, for what reasons? Without these data, the proposals made at the conclusion of the article, i.e., further study of the effectiveness of air purification and the development of a program to support the health of workers, are general recommendations for which it is difficult to specify the further path of research within the framework of sustainable development.
Minor notes:
1. The materials indicate only the brands of instruments on which the analysis was carried out, the carrier gas is not indicated, what column was used, the flow rate during the analysis, what database was used to identify substances, or whether these were internal standards. Authors are recommended to provide links to the analysis methodology if it was published by them earlier or to the methodology of another scientific team.
2. References to the tables of the supplementary materials are inconsistent in the text of the article, which makes it difficult to understand; check the sequence of mentioning the tables in the text or reorganize them.
3. Not all abbreviations in table S4 are described; it is advisable to provide links to open databases on the Internet.
4. Check the references to figures in the text, for example, page 2, line 76, there is no reference to figure 1.
Author Response
Comments 1: The question of the sources of emission of these volatile compounds has not been addressed. How does the composition of VOCs correlate with the composition of the raw materials used? Does the origin and species of trees used affect the VOCs emitted? The answers to these questions could also form the basis for the development of regulations for the assessment of VOCs in this type of manufacturing.
Response 1: The manufacturing process of the plywood manufacturing industry is introduced in detail in figure 1 and supporting information. The only raw materials used in the industry are raw trees and adhesives. From the point of view of the original material, the stacking, cleaning, and cutting stage of the tree will not emit VOC components such as formaldehyde, but the main component of the adhesive used is formaldehyde. Therefore, the two production processes involving the use of adhesives, the adhesive-coating and hot-pressing processes, are the sources of VOC emissions.
Comments 2: The article does not indicate what air purification measures are currently being used in the studied areas, how many employees and how much time do they spend in these conditions? If the air in the work area is not being cleaned now, for what reasons? Without these data, the proposals made at the conclusion of the article, i.e., further study of the effectiveness of air purification and the development of a program to support the health of workers, are general recommendations for which it is difficult to specify the further path of research within the framework of sustainable development.
Response 2: We have listed in table S2 that the VOCs purification measures used by the two companies participating in the survey are UV photocatalytic devices. In the calculation of health risk assessment, ET and EF denote the daily exposure time (assumed as 8 hours per day) and exposure frequency (assumed as 240 days per year), respectively; ED represents the exposure duration in years (assumed as 30 years based on statutory retirement ages in China: 50 for female workers and 55 for male workers). For organized VOC emissions, these harmful gases have been collected into the air purification device for treatment, and after purification, they are discharged through the exhaust pipe. The main hazard to workers' health is the unorganized emission of VOC gas in the workshop. Workers can ingest harmful gases through the respiratory system and thus endanger their health. Therefore, we further assessed the health risks of VOC components from unorganized emissions.
Comments 3: The materials indicate only the brands of instruments on which the analysis was carried out, the carrier gas is not indicated, what column was used, the flow rate during the analysis, what database was used to identify substances, or whether these were internal standards. Authors are recommended to provide links to the analysis methodology if it was published by them earlier or to the methodology of another scientific team.
Response 3: Thank you for pointing this out. We have further improved the detailed sample analysis method in supplementary materials.
Comments 4: References to the tables of the supplementary materials are inconsistent in the text of the article, which makes it difficult to understand; check the sequence of mentioning the tables in the text or reorganize them.
Response 4: Agree. We have readjusted the order of tables in supplementary materials.
Comments 5: Not all abbreviations in table S4 are described; it is advisable to provide links to open databases on the Internet.
Response 5: We have refined the description of all the abbreviations in table S4 and provided links to open databases on the Internet.
Comments 6: Check the references to figures in the text, for example, page 2, line 76, there is no reference to figure 1.
Response 6: We have further checked the reference to the graph in the text and added a reference to figure1 in the specified place.
