The authors have generally done a good job in addressing the concerns of the reviewers. I have a few remaining suggestions prior to publication in ACP.

Section 3.3.1 – I am still confused about how to interpret the MLR statistics. Are the ‘standardized relative importances’ presented in Figure 4 meant to be interpreted as 66% of PAN comes from biogenic precursors, as the text seems to suggest? In other words, in 2013, twice as much PAN comes from biogenic precursors compared to anthropogenic precursors. Or is it that twice as much of the variability in the amount of PAN is explained by variability in biogenics compared to variability in anthropogenics?

Page 2, L16 – NO is not reduced in this reaction, it is oxidized

Page 2, L17-18 – Would make more sense in the context of the paragraph to say that ‘Peroxy radicals compete with NO…’

Page 2, L18-19 The content in the boxes should be reformatted as reactions (R1,-1 and separately R2) and the equation should be listed separately as Eq 1

Page 6, L21-23 – This sentence is worded strangely. Why would RO2+NO reactions becoming faster make ozone production decrease? Isn’t it that NOx radical termination reactions become the dominant HOx sink?

Page 7, L6-7 “Most rural sites…” Do the authors mean that PAN was more sensitive to NOx at sites with low NOx, which tended to be rural? The sentence is not clear as written.