Dear Dr Zhang

many thanks for submitting your revised manuscript to ACP. I'll be happy to accept it for publication, subject to minor revisions (as detailed below), which I will oversee myself.

Yours sincerely
Jan Kaiser
Editor ACP

ACP requires use of the International System of Units (SI). Therefore, please add the word "concentration" after the symbols 127I and 129I where you refer to concentrations (starting with ll. 15, 19 and 19 in the abstract, but at many places elsewhere, too). Chemical element symbols on their own do not indicate the physical quantity. Please also change the axis labels to include quantity symbols and units in quantity algebra notation, e.g. γ(127I)/(ng m-3), for the mass concentration of iodine-127 [I have chosen the symbol γ rather than c to distinguish mass from molar concentrations], and N(129I)/(m-3), for the number concentration of iodine-129. Note that the word "atoms" should not form part of the unit. These symbols could also be used in the text for clarity and brevity, e.g. l. 78, "γ(127I), N(129I) and 129I/127I number ratios".

Referee #2 comment #6 on the relevance of boundary layer height for observed concentrations has not been addressed: Variations may occur even when emissions are constant. Your response should be reflected by appropriate additions to the manuscript.

Referee #2 comment #8: Again, your reply and revised figure is not included in the new manuscript. Also, there is a problem with your dates. The AQI value shows peaks in middle of March and early April, not middle of April and early May.

l. 12: Please give an institutional email address in addition to the private one.

l. 32: Replace "Whereas, " with "In contrast, "

l. 126: Please add gaseous emissions to this list.

l. 237 Please use SI units for mole fractions (nmol mol-1), not ppbv.

l. 364: This should be "influence of weather", not climate (as per the subsequent sentence of the same paragraph).

Many thanks for revising the paper so quickly.

I am happy with the corrections made except formatting of axis labels and the AQI data in Fig. 2e. Please follow the links to SI brochure and IUPAC Green Book given in the manuscript preparation guidelines:
https://www.atmospheric-chemistry-and-physics.net/for_authors/manuscript_preparation.html
Specifically, section 5.4.1 of the SI Brochure and section 1.1 pf the IUPAC Green Book give examples for the correct formating of axis labels. The unit is separated from the quantity symbol by a division symbol, e.g. N/(10^5 m–3). There should be no commas after the quantity symbol or multiplication symbols before the unit.
Table 1 and Fig. S4 still need quantity symbols for the concentrations, e.g. γ(O3)/(µg m-3), and other variables.

Forgive me if I am wrong, but the AQI data in Fig. 2e still seem to have much lower time resolution than the data in the figure provided in the response to the reviewers (cyan shaded area).