Chemical Composition of PM2.5 and Its Impact on Inhalation Health Risk Evaluation in a City with Light Industry in Central China
Round 1
Reviewer 1 Report
Introduction must include general information about PM2.5, p.e. importance, sources, human risk, etc. Not only references from studies in China.
Figure 1 must be improved.
Explain how did you apply the coefficient of divergente?
Althought the methods for ions chromatography are described in 16. Please describe them briefly.
Explain, why are the pollution periods due?
Abbrevations from table 1 must be explained in the caption, aldo for Figure 3.
Most the referencies used are from cities in China, for international readers would be interesting include references from studies aroud the world.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this paper, the authors report on the composition of PM2.5 at a light industry city in central China. They perform a PMF analysis to examine source contributions, and estimate toxic non-carcinogenic and carcinogenic health hazards due to inhalation of heavy metals. They state that there is no non-carcinogenic health risk, but the carcinogenic risk exceeded the risk threshold.
I feel that the author’s study is sufficiently novel and of sufficiently high scientific quality to merit publication. Unfortunately, there are a couple of aspects of the publication as submitted that are of such low quality as to warrant major revisions before I can recommend this for publication. Briefly, this is due to two main reasons: the description of the analysis of the health effects of heavy metals has been poorly and unclearly written, and a couple of the figures currently included are of very poor quality. In the case of one of these figures, the poor quality prevents me from properly reviewing the authors’ work. I provide more detail on these issues below.
General comments:
The authors need to make Sect. 2.4 more clearly written. They should state which elements are considered for the carcinogenic risk calculation, and which are not. They should specify before introducing the LADD that it is only calculated for carcinogenic metals, or that it is a step towards calculating the carcinogenic risk. The authors should include the full expansion of the LADD acronym: lifetime average daily dose. The authors should use the terms that match the letters of the acronyms they use: “hazard quotient” and “hazard index” for HQ and HI, “body weight” for BW, and “exposure duration” for ED. The authors should define the meaning of Rt. Is this an estimate of the lifetime risk of an individual developing cancer? The fraction of individuals that would be expected to develop cancer? The fraction of individuals that would be expected to die from cancer? Does this include all cancers? The authors repeatedly refer to HI < 1 as indicating no non-carcinogenic risk, but this is not true. The hazard exists, but it is below that due to the reference threshold. It could be characterized as “negligible”, or “not appreciable”, but it is not zero. The authors often use the word “risk” where they should use the word “hazard”. While these terms are interchangeable in lay language, they have distinct meanings in the health effects scientific community.
Several of the figures have been uploaded with extremely low quality. In the case of Fig. S2, the x-axis labels are illegible, and several of the % of species markers are not visible. This prevents me from adequately reviewing the authors’ PMF analysis. I note that the results of the PMF analysis are used throughout the rest of the paper, and referenced in Fig. 6, Table 3, and Table 5. I therefore feel that this is important enough that the paper must be reviewed again after a figure with legible x-axis labels has been included. The authors also may want to consider moving this figure from the supplement to the main paper, although this is not required.
The authors need to be careful and clear about using OC vs. OM. In Table 2 and Sect. 3.2.1, for example, the authors refer to OC, but the proportion of PM2.5 discussed suggests that they are actually referring to OM.
Specific comments:
p1, line 24: “no non-carcinogenic risk” The risk is small, but non-zero.
p1, line 29: “.11.Introduction” -> “1. Introduction”
p1, line 72: “It belongs to” -> “It has a“
p1, line 74: “Henan Statistical Yearbook” does not appear in the list of references.
p2, line 81: Do the authors mean “no more than 5 km between any two sampling sites”?
p2, line 83: Is this 11:00 am to 10:00 pm?
p3, lines 94-95: Wongphatarakul et al. (1998) used the coefficient of determination, but they did not suggest the use of a threshold of 0.2. Please include an additional source, such as Wilson et al. (2005) or Bell et al. (2011).
Also, “almost no difference in the chemical composition” is a little too strong a phrase, here. It would be more precise to say that “concentrations can be considered to be spatially homogeneous”.
p3, line 109: Here, the authors define MD as “mine dust”, but a note on Table 2 defines MD as “mineral dust”.
p4, line 132: (USEPA, 1989) does not appear in the list of citations.
p4, lines 141: Please use “averaging time” instead of “average time” for AT.
p4, line 141: BW is the average weight of what? Is this the average body weight of a human?
p4, line 143: Have the authors put Tables S1 and S2 in the opposite order that they intended?
p4, line 145: “If HI>1, it indicates that a risk of cancer exists.” Since the authors are here referring to the non-carcinogenic risk, this sentence is in error.
p4, line 146: “If HI ≤ 1, it indicates that there is no non-carcinogenic risk” This statement is false.
p5, lines 159-160: Please use either “μg/m3” or “μg m-3” consistently, do not mix the two forms.
p6, lines 191-192: Inconsistent font size.
p6, line 192: “0.9-1.6 times higher”: The authors should specify that this range refers to the interquartile ranges. Simply putting “(interquartile ranges)” after “0.9-1.6 times higher” would be sufficient.
p6, line 193: “in these two seasons”: Do the authors mean “between these two seasons”?
p7, lines 210-214: Do the authors have a reason to exclude biomass burning as a source of OC and EC?
p9, lines 240-241: Please add “in the same season” after “Compared with the clean periods”. Temperature in the clean spring and summer seasons were definitely higher than in the polluted autumn and winter seasons.
p9, line 245: [35] does not seem to be the correct reference here, it mentions neither SOR nor NOR. Please insert the correct reference.
p9, lines 260-261: “The recommended approach in previous studies was used to come to a suitable solution” The authors should very briefly (1-2 sentences) outline what the “recommended” approach was. They should also clarify why they chose the six factor solution as the optimal solution. This discussion should also be moved to Sect. 2.3.
p14, line 324: “The health effects…” -> “Some health effects…” The authors are assessing lifetime toxic or carcinogenic effects of inhaling heavy metals, but there are other health effects associated with particulate matter, including acute or long-term respiratory or cardiovascular effects, which are not usually linked to the concentrations of heavy metals.
p14, line 330: HI < 1 does not imply that there is no risk.
Table 1: Why are the annual average values of MD and TE so large, compared to the seasonal values? Even accounting for the differences in the lengths of the sampling periods, I don’t understand why the annual average value of MD is nearly as large as the Autumn value.
Table 1 & Figure 3: Is the summer mean of MD actually larger than the 95th percentile value? If so, this requires a special explanation. The autumn and winter mean values from the figure also seems to be smaller than the means listed in the table.
Table 1: “TE” is not defined in the table caption or the text. If this is “trace elements”, then how were the values calculated? Also, if this is “trace elements”, the authors need to make sure that they do not have a conflict of definitions with p3, lines 113-122.
Table 3: The total source contributions for Zhengzhou on pollution days sum to much less than 100%, and the source contributions for other days sum to much more than 100%. The source contributions for Xian in 2008 and Taian also sum to much less than 100%. This should be explained in the text.
Also, why is “Vehicle + biomass burning” listed under “other sources” for Taian, instead of being listed consistently with the results from this study?
Figure 1: Do the authors mean “Henan Province” instead of “Henan Privince”? Also, the labels of the sampling sites are nearly illegible due to poor image quality.
Figure 2: The winter season dates do not proceed linearly: The current sequence is 1/19, 1/22, 1/30, 2/2, 2/5, instead of 1/19, 1/22, 1/25, 1/28, 1/31, 2/3, 2/6. Please fix this. Also, if possible, please make the breaks in time between seasons clearer.
Figure S2: The figure is blurry and the labels are illegible. Please upload a higher-quality image. Also, it would be good to have the x-axis labels under each subplot. If more space is needed, the legend does not need to appear in each subplot, just once for the figure would be fine.
Citations:
Bell, M., Ebisu, K. & Peng, R. Community-level spatial heterogeneity of chemical constituent levels of fine particulates and implications for epidemiological research. J Expo Sci Environ Epidemiol 21, 372–384 (2011). https://doi.org/10.1038/jes.2010.24
Wilson, J. G., Kingham, S., Pearce, J., & Sturman, A. P. A review of intraurban variations in particulate air pollution: Implications for epidemiological research. Atmos Environ 39(34), 6444-6462 (2005). https://doi.org/10.1016/j.atmosenv.2005.07.030
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript exhibits high technical quality, the experiments are done very solidly and the conclusions are correct. It is not very original - as one another study of the state of air in one another city. Nevertheless, I think it is worth publishing as a good example of how to assess air quality, what can be helpful for public health institutions in various parts of the world.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The revised submission has addressed my concerns, and merits publication with minor revisions. I list a small number of additional corrections below.
During their revisions, the authors corrected “mineral dust” to “mine dust”. I appreciate the consistency, but it is clear that the substance that the authors are referring to throughout the paper is mineral dust (dust composed of minerals, defined by its composition), and not mine dust (dust whose source is mining operations, defined by its source). Therefore, “mine dust” should be corrected to “mineral dust” throughout the paper.
p2, line 80: 11am to 10pm the next day would be 35 hours. Do the authors mean 11am to 10am or 11pm to 10pm?
p3, lines 93-98: There seem to be some errors in the definition of COD. Cij does not appear in eq. 1. I assume that the authors mean "coefficient of divergence" instead of "divergence coefficient". The phrase “number of components” should be replaced with “number of chemical components”. Please also subscript i, j, and k after x. Also, the font is not consistent here.
p3, line 103: “(2001A, the American Desert Research Institute, USA)”: This citation does not appear in the list of references.
p4, line 125: do the authors mean g L-1, instead of lg L-1?
p4, line 155: Please replace “risk of non-cancer” with “non-carcinogenic toxic risk”.
p8, line 249: “minel dust” should be corrected to “mineral dust”. Note my comment regarding mine dust and mineral dust above.
The text on Fig. 1 is still a bit blurry, though it is now legible. The authors should upload a higher-resolution image, if they can.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
