Source Apportionment of Air Quality Parameters and Noise Levels in the Industrial Zones of Blantyre City

Round 1

Reviewer 1 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

dear authors,

thank you for considering my suggestions and for modifying the paper as requested.

Author Response

Dear reviewer,

We are very grateful for your comments on how to improve our work. 

Thank you

Reviewer 2 Report (Previous Reviewer 4)

Comments and Suggestions for Authors

The authors have improved the manuscript compared to the previous version.

As a minor comment I suggest the authors remove the lines 184-190 (of updated version) providing some technical features regarding the HYPLIT model.

In Line 527: Is "Table 3" correct or you should change it with "Table 4"? 

Author Response

Dear reviewer.

Your comments on the manuscript were very helpful. They have  helped us improve our work.

All the second suggestions have been addressed.

Thank you 

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 Authors

Thank you for the opportunity to review. If possible, consider the following suggestions: - line 373, reinforce the aspect of the presence of cement and lime dust by providing literature items to improve visibility on axes (Fig. 11-14).

It was written that the Drager X-am 7000 device was used to measure air quality, please provide the method of verifying the measurement results (was it a reference gas? What were its parameters?) - line 130.

Author Response

Thank you for the opportunity to review. If possible, consider the following suggestions: - line 373, reinforce the aspect of the presence of cement and lime dust by providing literature items to improve visibility on axes (Fig. 11-14).

This comment is well appreciated, and it has been updated accordingly in the revised manuscript (Pages 11-17).

It was written that the Drager X-am 7000 device was used to measure air quality, please provide the method of verifying the measurement results (was it a reference gas? What were its parameters?) - line 130.

This is well noted.  Drager X-am 7000 device was used to measure CO.   Dylos DC1100 PRO Laser Particle Counter (2018 model) were used to monitor PM10, PM2.5 and TSP. The method used for verifying the measurement results was such that, before sampling, monitors were calibrated in air which was free of the gases measured according to the instrument operational manual provided by the manufacturer (Page 4).

We are grateful for the comments raised in here and from other reviewers as well. 

Reviewer 2 Report

Comments and Suggestions for Authors

The article entitled "Source Apportionment of Air Quality Parameters and Noise Levels in the Industrial Zones of Blantyre City" presents an interesting and novel study that attempts to show the relationship between air pollution and noise pollution.

In general, the manuscript is well written and developed. The methodology is clearly explained and the results are reflected. However, I have a few recommendations:

Introduction: Line 59: What do you mean by a three-factor solution for the PMF?

Figure 1: Shows a grey line for MS 8 standard hours, but this line is not observed in the figure.

Figure 4: Shows a yellow line for the WHO 24-hour standard, but this line is not observed in the figure.

Correlation between air quality parameters and noise levels: what is the significance of the correlations?

Author Response

We are grateful for the comments raised in here and from other reviewers as well. 

Thank you

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article under review concerns the source apportionment of CO, PM2.5, PM10, and the total suspended particles (TSP), along with the determination of noise levels in several industrial areas of Malawi. The authors carried out the sampling of the earlier mentioned parameters in two distinct days: the first one in February, the second one in August to find their mean levels,  their possible spreading trajectories, and their source apportionment. Moreover, they investigated on the possible correlations between the noise levels and the air quality parameters considered (CO,PM2.5, PM10, and TSP). This study, thus, falls in the scope of the journal to which has been submitted. The structure of the paper is well designed: the issue addressed in the paper is adequately introduced in the introduction section, the materials and methods section, the results, and the conclusion sections present the correct contents. However, in my opinion, major flaws characterize the manuscript. The relevant points can be summarized as follows:

1.       The authors do not clearly tell the number of days during which the monitoring has been performed. Only by viewing figure 5 or figure 9, it is possible to understand that, only on the 17^th of February and on the 23th of August, the measurements were performed. If this is not true, the authors must tell how many days the experiment lasted. If it is true, in my opinion, considering only two days of measurements is really too little to draw any conclusion making any sense. In this second case, the experiment should be repeated by considering a congruent number of days, and data should be elaborated on the base of a more representative dataset.

2.       By leaving apart the issue exposed in the last point, the 2.5 section of the manuscript lacks of important elements to understand the study. The HYSPLIT model is used to calculate the possible trajectories of the pollutants. The spread of pollutants in the air depends on various factors, such as for example, the wind direction and strength. By reading the manuscript, nothing is clear about these data, nor it is explained in which way such data are taken into account, measured, or considered.  The authors should adequately clear these elements, expose these data, and explain how they affect the pollutants spread.

3.       The PMF method was selected to perform the source apportionment of pollutants. The authors do not explain how the results found are related to the Factors characterizing the PMF algorithm. Factor1 is related to the plastic manufacturing industries? Why?... and so on for all the other factors. The authors cite at line 358 “the Factor Analysis in section 4.6.2”, but the section 4.6.2 does not exist. Moreover, Signal to Noise ratio are exposed for the pollutants, but what is this parameter? What’s the meaning in the case of pollutant concentrations? The Signal to Noise ratio is a parameter typical of electronic signals, so, why is it used in this study?  In conclusion, the source apportionment method followed to determine the pollutants sources is not clear and really confused, thus, it is almost impossible to understand how the gathered data lead to the conclusions exposed.

4.       Figure 11, 12 ,13, 14 are almost unreadable. The legend text is too much little to read. Even enlarging the figures, I cannot correctly understand their meaning.

5.       The correlations between AQP and noise levels exposed in table 5 are all below 0,5. A moderate or strong correlation between two variables  means a correlation parameter above 0,5; for this reason, the noise levels and AQP are weakly correlated, thus, the sentence at lines 461-462 in the conclusion section stating that “air quality was seen  to be viable for use as an indicator of noise pollution” is completely wrong.

Comments on the Quality of English Language

The english language needs little corrections.

Author Response

We are grateful for the comments raised in here and from other reviewers as well. 

Thank you.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Comments to the Author

Review of Article “Source Apportionment of Air Quality Parameters and Noise Levels in the Industrial Zones of Blantyre City” by Constance Chifuniro Utsale, Chikumbusko Chiziwa Kaonga, Fabiano Gibson Daud Thulu, Ishmael Bobby Mphangwe Kosamu, Fred Thomson, Upile Mawenda and Hiroshi Sakugawa.

This article deals with the air quality parameters (CO, TSP, PM 2.5, PM10) and noise levels in the industrial zones of Blantyre city. The authors have shown the period (dry/wet) mean concentrations of studied pollutants and also they have implemented a PMF analysis in order to identify the key factors that influence AQPs accumulation.

In my opinion, this work needs improvements in order to be published in Air Journal. I believe that this article has the potential to be published in Air Journal after a Major revision. The authors could take under consideration the suggestions and comments below.

·         Lines 20-22: The authors said that “In the wet season, mean concentrations of CO, TSP, PM10, and PM2.5 20 were 2±1.46 mg/m3, 319±79.35 µg/m3, 36.2±17.72 µg/m3, and 27.1±13.32 µg/m3, respectively. Dry season concentrations increased to 4.33±2.31 mg/m3, 52.3±5.61 µg/m3, 47.8±16.68 µg/m3, and 35.8±12.58 22 µg/m3.”

 Is it correct that the TSP (wet season) is 319±79.35 µg/m3 and the TSP (dry season) is 52.3±5.61 µg/m3?

·         I suggest Table 1 move to appendix.

·         Section 2.2: I suggest the authors refer the period of the study (Which are the number of wet and dry seasons that is implemented in this campaign?)

·         In lines 135 – 137 the authors said that “During data collection, 10 min consecutive average measurements were recorded in an excel sheet during morning (09:00 - 10:30), 136 midday (11:30 - 13:00) and afternoon (15:30 - 17:00)”

Why do the authors select these times during a day as representative for the analysis? Is there a specific reason for example regarding the industrial activity?

In my opinion sections 2.4 and 2.5 should be merged in one section.

·         Section2.5:  I suggest the authors present a bit more elements regarding the HYSPLIT model.

·         In Table 2: do the numbers show that mean values plus/minus one standard deviation? Could you please clarify this point?

·         Figure 2 is missing from the text. Please correct.

·         The authors have 2 Figures as “Figure 1” in the text. Please correct this point. Also, in Figure 1 (line 224) the gray line (MS 8hr Standard) is missing.

·         In lines 234-235 the authors said that “…in the dry 234 season it was 76.3 µg/m3”. In the abstract (lines 21-22) the authors said that “Dry season concentrations …, 52.3±5.61 µg/m3…). Could you please correct with the appropriate values these points all over the text?

·         In lines 236, 297, 308 please remove the extra gap.

·         In line 247-248 please remove “100 percent” with “100%” – please keep the common notation all over the text “percent” or “%”

·         In section 3.1.3 the authors present data from Figure 7 before the presentation of Figure 6. I suggest to follow the correct numbering in Figures

·         Could you please improve the quality of Figure 11. I suggest the authors enlarge the axis numbering and legends in order to help the readers to read these plots. 

·         In Table 4: what about the statistical significance of presented correlation coef. Values.

Author Response

We are grateful for the comments raised in here and from other reviewers as well. 

Thank you

Author Response File: Author Response.pdf