Comments

The manuscript presents a laboratory study of the commercially available SwisensPoleno system, advancing its use for MP identification with a optimised CNN using holography and fluorescence data for the highest classification accuracy. Overall I am very pleased to have reviewed the manuscript, however, I am not clear if the model trained can be used for live measurements and why there were no measurements using a combination of particles to test the system. From what I understand 15 different airborne particle groups have been measured for holographic and fluorescence data, which was later trained and test in 3 models in an offline process.

Expanding on this if the study had an example dataset to finish that had resuspended already collected environmental MPs (or mixture of the 15 tested particles) this would provide a more convincing argument for its use and is shown in examples of other novel sampling or analysis methods. It would further reinforce the later results discussion and conclusions on the SwisensPoleno system and CNN use and impact of environmental samples and their varying fl response which would affect classification.  I do appreciate that this is and is stated as a laboratory study only.

Given the manuscripts main development are the models and datasets created it would be good to see this hosted in an opensource platform, referenced in the text, so that other researchers could access it and build on it.

To fix/address:

Lines 3 – 33: Abstract, please include the models you used, ML is fairly ambiguous, even if you just state the most optimal model that is fine.

Lines 30-33: Abstract, stating that the holo+fl model was the most optimal, this is a key result and adaption of the existing MeteoSwiss model,  but is not mentioned.

Line 46: MPs are in the majority of publications classified into the 1-5,000um scale, to fit your classification us more I would also add in the newer ISO ruling on size as well as the publication you have referenced. This is a better justification in my opinion (https://www.iso.org/files/live/sites/isoorg/files/store/en/PUB100472.pdf)

Line 55-65: All references are fine, but none are particularly recent, there are many reviews and also studies that show the detection of MP and NP that could be used. Just an observation that doesn’t have to be addressed but was surprising to see.

Line 117-127: Fl measurement regions, further explanation of why these regions would be appreciated (not only that this is what is available through the SwissPoleno), in MP research there is some debate on what wavelength to use and filter at. This could be an extra comment added to the SI given to support researchers more deeply involved with this aspect.

Line 128-133: Clarity on why MeteoSwiss not used, also can a custom python script be loaded to the system? MeteoSwiss can be trained and updated but is its current supervised learning method not useful for MP analysis?

Line 143: Materials section: I would like to confirm why PS was not considered for analysis as it is one of the major MP polymers detected in aerosols, it is also available from Cospheric and Goodfellows. A comment later in the discussion could cover these questions as other MP researchers would have. Is the statement in line 459 related to this?

Line 212: Please state the water quality value.

Line 223: Added details on the flow rate limits and particle size limits of the system would be good to add here, or in section 2.1. The questions I am thinking while read are, is there a reason no PM2.5 particle sizes were assessed (PS would be the only standard easily availably in this size range), is it because the SwisensPoleno has a detection limit. Secondly is there a flow rate limit as well. A web search of the system does not give much results unless in it’s the Mars of Jupiter variant.

Line 227-233: Dataset creation. Will you make this dataset available as an open data source, same goes with the model. Since this is a large aspect of the work I would expect to see this hosted somewhere, University server, Github or other so that the scientific community and others can make use of the data/model and build on it.

Line 261: Can you explicitly confirm here if CNN is used for the holo+fl or not.                         

Line 375-377: Could you expand your discussion to PA, PMMA and PA as they seem less distinct from the UMAP. Is there any further discussion that can be given to the important of dimensions 1 and 2 in the UMAP plot, are these evenly weight in terms of dimensionality? I am thinking along the lines of k-means plot dimension value assignment.

Line 387 – 500: Need to check classification values given and how stated, several read as incorrect or misleading, detailed in next comments.

Line 402: Should this be 78%?

Line 417: 93%?

Line 426 – 427: Please confirm the model used here.

Line 430: is this not less than 98% accuracy?

Line 449: related to line 402 accuracy reporting

Line 502-506: Should state for singular MP polymer groups? The sentences make it sound like you have measured all the particle types together which from my understanding is not the case.

Line 505: Can you claim that it is in real time classification, not an in real time measurement? My understanding is that individual particle types where measured. Later the analysis was made.