Indoor Air Quality Intervention in Schools: Effectiveness of a Portable HEPA Filter Deployment in Five Schools Impacted by Roadway and Aircraft Pollution Sources

Round 1

Reviewer 1 Report

This study presented intervention of indoor air quality in schools, by using a portable heap filter to measure the particles near the roadway and aircraft pollution sources. This is an interesting topic, the writing is well acceptable, the structure is good enough, my only minor comments would like to make the article clearer and well presented.

(1) Reviewer suggest to provide a map or schematic diagram to present the site info. “The schools participating in this project were located within a 7-mile radius of Sea-Tac International Airport and within 0.5 mile of an active flight pat”. The authors will know the details.

(2) Reviewer would like to see the detailed measurement, how about the test process? What is the test location in the school classroom? How many interval of samples? Some pictures may be required.

(3) Some pictures were too small, reviewer suggests to enlarge them and each picture may take whole column, which is fine.

 

(4) The reference format was inconsistent. Please revise that. Also, an abbreviation table may be required. 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript compare the concentration of outdoor and indoor ultra fine particle (UFP) with and without the High Efficiency Particulate Air Filter (HEPA) in 5 schools near the airport. Overall, this study is novel due to limited study focused on ultra fine particle especially indoor ambience. However, there are a few comments and/or issues that need improvement/ clarification from the authors:

1. The introduction lack of scientific literature that explain regarding UFB especially on association of UFB and regression model. The main objective stated was to evaluate the performance of the proposed HEPA in order to reduce the indoor pollutant, however, there were some statistical tests that were conducted without detailing the proposed of conducting it.

2. The methods were not structured. The details of monitoring especially on correct procedure (appropriate height of the sensor) for indoor monitoring was not detailed out. Why author did not follow the method as described in ASHRAE for indoor monitoring? Why you need an empty space for monitoring? The condition of the classroom was also not specified. Is the classroom was fully air conditioned or natural ventilated with the support of mechanical ventilation? The outdoor exchange rate procedure that was included in the nonpublished material should be included in the manuscript with proper citation. In addition, the main flaws of the method was the number of sampling. The authors only conducted 4 days in total for sampling of UFP in the five schools which were very inappropriate. The obtained outdoor and indoor varies everyday according to the surrounding activities. Hence, more samples can normalised the UFP concentration compared to only 1 sample/ season. Furthermore, the statistical analysis described in the methods was not comprehensive. All the methods used must be included in the method. For example, in the results there were wilcoxon rank test and pearson correlation mentioned, but no details of it in the method. The results of PCA was also included in the nonpublished materials. As I mentioned above, the objectives were not properly described, hence the direction of this manuscript was quite clueless.

3. The quality of graphical presentations are acceptable but some of the results presented only for 1 school, hence no comparison can be made (Figure 3). In Figure 2, the outdoor concentration shows significantly different variation, how do you normalised that? There were no results of Pearson correlation but it was described in the manuscript. For the log-log model, why the outdoor concentration was fixed at 5000 #/cc? Any justification? The authors also presented the spatial distribution of the flightpaths that I could not see the relation with the study areas and the effectiveness of the HEPA.

4. In discussion, the authors should relate the findings in this manuscript with comparison with other study. However, in this manuscript it was done vice versa.

5. The conclusion was not supported by the results.

The details of comments was given in the attached document.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Overall, the revised version was more structured and clear compared to the 1st version. The authors had answered almost all the issues and comments from the previous version with major amendments were done especially in the method section. 

There are 2 things that the authors need to check:

1. There was no error bar in Figure 5 but the error bar is described in the figure caption.

2. I still think that the spatial distribution of arrivals and departures (figure 9) does not need to be included in this manuscript. Table 7 & 8 itself is enough to describe the distribution of flightpath. If you later remove the figure, please rename the section accordingly.

Author Response

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Author Response File: Author Response.docx