Dear authors.

Please address the reviewer remaining comments reproduced here: “I have two remaining comments. First is that the limitations of using the OFR should be acknowledged in the conclusions section of the paper. In particular, in the second to last paragraph the differences in dilution in the real atmosphere versus the OFR and the implications for changes in particle composition need to be acknowledged. Second, I think that the pie charts of peroxy radical fate in the OFR included in the response document are valuable and should be included in the SI. This chart allows the reader to fully appreciate how much the RO2+OH reaction is enhanced (non track changes version line 367).”

I only have minor suggestions:

Line 83: you may want to use classic references to mutagenicity of PACs by Pitts from the 60s, which are also summarized in Chapter 10 of this book: “Finlayson-Pitts, B. J.; Pitts, J. N., Chemistry of the Upper and Lower Atmosphere: Theory, Experiments, and Applications. Academic Press: San Diego, 2000; p 969 pp.”

Figure 4: should all the factions shown add up to 1? Two of the bars (6.8d in S-5% and 4.0d in S-22%) do not seem to, and it is not clear what the base for the normalization is in that case.

Figure numbering in the text needs some work. Figures in the paper are called almost in order: 1, 2, 4, 3, 5, 6, 7, 8, 9, 10, so only one permutation is needed. However, the supporting information figures are completely out of order, appearing in sequence of: S9, S5, S7, S1, S2, S3, S4, S15, S6, S10, S11, S8, S14, S12, S13, S17, S20, S16, S18, S19. The number of supporting information figures make the paper a little overwhelming to read. I would recommend prioritizing them and perhaps removing ones with the lowest level of priority.

Given the size of it, the SI section would strongly benefit from a table of contents.