Spatial Concentration of Carbon Components in Indoor PM2.5 of School Classrooms in a Large City of Korea
Round 1
Reviewer 1 Report
Real interesting work and relevant.
introduction: may be extended with more examples of similar or relevant results and overall context.
References: appears that the authors cite mostly local and Asian papers. I recommend that the authors look for similar work and papers, relevant also from different parts of the world.
Author Response
Introduction: may be extended with more examples of similar or relevant results and overall context.
Ans. Since, so far, there are not not many school studies worldwide, it was difficult to find relatively comparable literature. A few more recent studies have been added with relevant discussion.
References: appears that the authors cite mostly local and Asian papers. I recommend that the authors look for similar work and papers, relevant also from different parts of the world.
Ans. In recent days, Asian countries are suffering from severe air pollution, and various researches are being conducted. Thus, we cited relevant references, but now we also add a few references telling the experiences of developed countries.
Reviewer 2 Report
The work presented a very important investigation for PM2,5 in schools. Work is well presented and very well written. I think it is very important to describe the measurement devices-what kind and their accuracy.
Author Response
I think it is very important to describe the measurement devices-what kind and their accuracy.
Ans. As mentioned in Experimental Design chapter, we used a methodology that frequently used in other works. Two new references describing are now added to the chapter of measurement and analysis.
Reviewer 3 Report
Please review the uploaded file with detailed comments
Comments for author File: 
Comments.pdf
Author Response
The paper adds to the literature but does not clearly articulate how the findings can be used/ what recommendations emerge from the study.
The average level of pollutions is reported to be lower than the National Guideline values; does it mean that the children are in a safe environment?
Ans. The current concentration of PM2.5 in the classroom for the class hours is lower than the national guidelines.
How far from the main road where each of the schools? How the National Guideline value compares to the WHO recommended targets?
Ans. Summary of test schools has newly been added in Table 1.
For reference, WHO - 50 and 25 ug/m3 for Pm10 and PM2.5 respectively, which are more strict than Korea.
The paper uses terminology as indoor ‘dust’. ‘Dust’ has a wider definition and does not include only air pollutants. Authors are encouraged to check terminology accuracy and consider changing the word dust to something more clearly defined such as ‘air pollutants’ or similar. Then paper also needs a careful proofread/ English check.
Ans. Dust has been rewritten into particulate matters as appropriate for the context.
Abstract
The abstract should include reference to where the study has been conducted, include the national guidance level numeric values to facilitate the comparison with the study results and have a stronger closure with a key final message.
Ans. Numeric values of National Guideline has been added.
Introduction
• The introduction could be made more compelling and make further reference to other countries in the region and why the problem is so important.
Ans. Several references have been added and discussed.
• How the values reported in lines 35-43 should be interpreted? For example, authors need to help the reader understand the health implications of an indoor to outdoor ratio varying from 1 to 1.9. (i.e. Which ratio is safe for health, which ratio is dangerous?)
Ans. Two sentences have been added to emphasize the importance of indoor carbons.
• Please clearly spell out the research questions addressed by this study
Ans. The purpose of this study has been rewritten in the last paragraph of Introduction.
Thus, to investigate carbonaceous aerosols in school environment, particulate matters such as PM2.5 and PM10 were sampled and quantitatively analyzed from classrooms and playgrounds. This study also focused on the daily class hours of students. The obtained data will be fruitfully used in establishing the national school environment management policy.
• Was ethical approval granted for this study? Why the Ministry of Environment supported the research/ how is it going to use the results?
Ans. ME has approved the publication of our research results, and the obtained data will be used to establish the school air quality management policies.
• Please rectify grammar / missing words errors (e.g. line 28)
Ans. We have carefully reviewed and corrected typo and grammars. And received a proofread by an official editorial.
• Line 36 - Indoor pollutants present are particularly dangerous because they are intensively exposed to residents – please review this sentence as it is grammatically wrong
Ans. The sentence has been rewritten.
• Check consistency of acronyms definition (e.g. OC was first defined in the abstract and not redefined in the introduction as opposite to EC)
Ans. All the acronyms and abbreviations are now revised.
Experimental
• Should this section be called differently (e.g. “materials and methods” or “experimental design”?
Ans. The subheading is changed to Experimental design.
• Line 52 – the number of school taking part in the study should be clearly stated in this section.
Ans. It is added as well as in Table 1.
• It is also recommended to have a summary table reporting basic characteristics of the schools (i.e. distance from main road, proximity of other sources of exposure, number of classroom sampled, number of pupils in the school etc.)
Ans. A new table is added (Table 1).
• Please elaborate further on the sampling. Were the 4 days measurements repeated between October and December every week or were there a one off? How many measurements each class received? Why the measurements were taken for 4 days and not 5 days in a week?
Ans. One day is for preparation, thus we could work for 4 days a week.
Results and discussion / Conclusions
I recommend splitting the results section from the discussion and have a separate discussion where the reader is helped to fully understand and interpreted the presented results.
Ans. As for a scientific article, we decided that it would easier to understand if 'Results and Discussion' were combined. Please acknowledge our intentions.
Authors needs to make a more compelling case on why it is important to look carbon species and chemical composition of PM2.5 and PM10 in general.
Ans. We added a few more sentences to emphasize carbonaceous species with regard to indoor PMs.
Also the discussion should present and compare what has been reported in other studies in the same city or similar cities in other countries.
Ans. No studies have been done for domestic schools. Several references have been additionally discussed in Introduction and Results and Discussion.
I am surprised to see that the classroom measurements where done only for 8 hours and not 24hr hours which would make the results of the study comparable to the national daily average. Are authors sure a direct comparison between the two values can be done? The authors should justify their choice and their interpretation better.
Ans. Based on our preliminary studies, indoor concentrations of after-school were very low, approximately one-third of day time. We focused on harsh conditions, thus sampled during the class hours.
Everything reported under the conclusions and the Figure 6 should be moved to the discussion and the conclusion should focus on the ‘meaning’ of the obtained results rather than just reporting the measured values.
Ans. We decided to delete Figure 6, which overlaps with discussions above.
What is the final message authors want to convey to the readers? How schools or the Ministry of Environment should act based on the study findings?
Ans. Thus, school locations and building niches should be carefully managed to minimize carbon exposure to young students.
Round 2
Reviewer 3 Report
Thank you to the authors for the revisions and improvements made to the manuscript. Not all my comments have been fully addressed plus I have noticed a few other aspects to be improved.
Title / Abstract: Please add reference to Korea or the city where the study took place in both the title and abstract of the manuscript.
Please add a closing statement to the Abstract. Something like “ this data will be used to inform the establishment of a national school air quality management policy” or which stakeholders will be interested in learning from the study results.
The article still needs a further English proofread although authors may have already sought editorial advice. All typos and errors should have been tracked but they weren’t. I have marked and suggested some language improvement below.
Line 42 – Suggested re-writing as following: “Contaminants present indoor spaces are particularly dangerous because they can be intensively be inhaled by residents” // or “Residents are at high risk of exposure from contaminants present in indoor spaces”
Line 44 – Suggested rewriting as the following or similar. “In accordance, higher I/O ratio would be undesirable given the likely negative health effects for indoor occupants”
Line 50 – Please specify “A study by xxx” or the country where the study was conducted
Line 57-58: The obtained data will be fruitfully used to inform the establishment of the a national school air quality management policy.
Line 65: Please rephrase with something like the following: “Five public elementary schools took part in the study. They are located between 137 m to 669 m from the main road”. Also please add “ Within each school, 3-4 classrooms took part in the study”
Line 101: Table 1. A column call ‘floor’ was added. Is that the floor of the school where the class was located? If so, it may be best to change it to “classroom’ floor’ and use 1st, 2nd etc. to indicate the floor.
Lines 153-157: Please re-check sentence 153-154. Meaning not clear (how briskly active children impact concentrations)?. In addition, the two sentences appear to mean that both School E-1 and E-5 show little difference in PM2.5. Please revisit.
Class- 153 rooms of school E-1 showed little difference in PM2.5 concentrations from the outside, 154 probably due to briskly active children
Line 173: define S and Cl the first time they appear
Line 158. Can authors elaborate slightly on why “The atmospheric PM level of Korean fall season is usually lower than other seasons”?
Line 211: check English of this sentence “OC absorbed in fine mode of particulates”
Line 212: Spell out PAHs and keep the acronym in brackets.
Line 251: Acronyms should be used (they have already been defined before). I note reference to inorganic carbon with EC acronym being used
Figure 4. Can the ion names in the figures be fixed (e.g. SO42- should be SO42-
Conclusions
Lines 323 -324. The opening statement of the conclusions needs to include the number of schools sampled (5) and report the city where the measurements were taken for clarity (some readers may start by reading the conclusions).
Line 328. Authors need to repeat that the obtained values are below the national standard and they found that current concentration of PM2.5 in the classroom lower than the national guidelines.
Should any recommendations on sulfur content be given? Authors find that the level is 27.9% indoor. Is this level dangerous for health?
Author Response
Title / Abstract: Please add reference to Korea or the city where the study took place in both the title and abstract of the manuscript.
-> we added ; in a large city of Korea
Please add a closing statement to the Abstract. Something like “ this data will be used to inform the establishment of a national school air quality management policy” or which stakeholders will be interested in learning from the study results.
-> As commented, we added a closing statement : The current data obtained in this study can be used to inform the establishment of a national school air quality management policy.
The article still needs a further English proofread although authors may have already sought editorial advice. All typos and errors should have been tracked but they weren’t. I have marked and suggested some language improvement below.
Line 42 – Suggested re-writing as following: “Contaminants present indoor spaces are particularly dangerous because they can be intensively be inhaled by residents” // or “Residents are at high risk of exposure from contaminants present in indoor spaces”
-> as indicated; the sentence has been revised.
Line 44 – Suggested rewriting as the following or similar. “In accordance, higher I/O ratio would be undesirable given the likely negative health effects for indoor occupants”
-> rewritten.
Line 50 – Please specify “A study by xxx” or the country where the study was conducted
-> a phrase has been added : a study carried out in China,
Line 57-58: The obtained data will be fruitfully used to inform the establishment of the a national school air quality management policy.
-> Rephrased.
Line 65: Please rephrase with something like the following: “Five public elementary schools took part in the study. They are located between 137 m to 669 m from the main road”. Also please add “ Within each school, 3-4 classrooms took part in the study”
-> rephrased.
Line 101: Table 1. A column call ‘floor’ was added. Is that the floor of the school where the class was located? If so, it may be best to change it to “classroom’ floor’ and use 1st, 2nd etc. to indicate the floor.
-> they are classroom level, so revised as your comment.
Lines 153-157: Please re-check sentence 153-154. Meaning not clear (how briskly active children impact concentrations)?. In addition, the two sentences appear to mean that both School E-1 and E-5 show little difference in PM2.5. Please revisit.
-> Edited like this: The difference between indoor and outdoor PM2.5 concentrations in school E-1 was not as high as in other schools, perhaps because the children were more active as well as frequent window opening.
On the other hand, the E-5 was found to significantly lower indoor PM2.5 , where teachers closed windows and operated air purifiers due to poor outdoor air quality outside.
Line 173: define S and Cl the first time they appear
-> rewritten: sulfur(S) and chlorine(Cl)
Line 158. Can authors elaborate slightly on why “The atmospheric PM level of Korean fall season is usually lower than other seasons”?
-> the sentence is now revised as : In Korea, the atmospheric PM level in autumn is generally lower than in other seasons, in which barometric flow is fast and local atmospheric circulation is smooth, is usually lower than other seasons [11].
Line 211: check English of this sentence “OC absorbed in fine mode of particulates”
-> Rewritten with a reference: OC adsorbed on fine particles contains very harmful components including polyaromatic carbons (PAHs) [18].
Line 212: Spell out PAHs and keep the acronym in brackets.
-> rewritten: polyaromatic carbons (PAHs).
Line 251: Acronyms should be used (they have already been defined before). I note reference to inorganic carbon with EC acronym being used
-> revised as : While EC is generally thought to not undergo chemical transformation once emitted
Figure 4. Can the ion names in the figures be fixed (e.g. SO42- should be SO42-
-> re-editted.
Conclusions
Lines 323 -324. The opening statement of the conclusions needs to include the number of schools sampled (5) and report the city where the measurements were taken for clarity (some readers may start by reading the conclusions).
-> we specified 'Seoul' and 'five schools'.
Line 328. Authors need to repeat that the obtained values are below the national standard and they found that current concentration of PM2.5 in the classroom lower than the national guidelines.
-> A sentence has been added: The currently obtained level is below the national standard except one classroom.
Should any recommendations on sulfur content be given? Authors find that the level is 27.9% indoor. Is this level dangerous for health?
-> 27.9% is a relative proportions of chemical elements. However, the absolute amount is extremely low and safe enough.
Round 3
Reviewer 3 Report
I am satisfied with the corrections provided.
