May I ask you to address the minor/technical comments by the referee in an updated manuscript for submission. Thank you. I copy them here for your convenience.

Fan et al present a revision of their manuscript reporting HCl and HBr observations in Beijing. The revisions made in response to reviewer comments significantly strengthened the manuscript. In particular, the reporting of uncertainties and LODs is important and useful. The move of now Figure 5 to the main text and associated caption and discussion edits are also excellent revisions that strengthen the manuscript. Similarly, the revisions to Figure 8 and added comparison of HCl and HBr on “clean” and polluted days are excellent.

I only have one remaining minor comment. It is not clear why the HCl and HBr concentrations represent lower limits (Line 257 of tracked changes version), as the reasoning for this is stated to be due to unquantified uncertainties such as different sensitivities to HCl and HBr, which reflect understanding of the value but not the directionality (lower/upper).

This is an interesting study presenting new measurements of HCl and HBr in Beijing. I only have a few minor comments that the authors should consider addressing.

1) Use of [NO2][OH] as proxy for HNO3
Line 316. “HNO3 which was indicated as [NO2]*[OH]” I don’t understand this statement. Are the authors measuring NO2, calculating OH, and then assume that the product of the two is proportional to HNO3? This doesn’t seem correct. NO2+OH is certainly one pathway for HNO3 production, the other being heterogeneous reaction of N2O5 on aerosols, which is likely quite important in winter. Furthermore, the lifetime of HNO3 is much longer than that of NO2 or OH, so the product of [NO2][OH] might not be a good proxy for the actual HNO3 concentrations. It might be more useful to plot NO2 and OH separately on figure 3.

2) OH calculation
Line 315 and supplemental info. The method and justification for calculating OH is not very clear. It seems that it is based on JO1D and NO2 measurements and based on inferred JNO2. S8 cites 2 papers: Xu et al. and Tan et al. It is unclear whether the empirical fit from Xu et al. (2015) in equation S2 was originally obtained from observations of OH concentrations or model calculations. Also, the authors then go on to say (SI, lines 359-365), that they use the results from Tan et al. (2018), which they mention is only a function of JO1D. Can the authors clarify the whole section? What equation do they use (the one from Xu or from Tan)? What is that equation based on? Pure model calculations (and if so, what are the main sources of OH?) or actual observations of OH?

Additional comments:
Page 4 line 187: “is of necessary” should be replaced with “is necessary”

Page 6 260 “due to a direct calibration for HBr” should be replaced with “as direct calibration for HBr”

Line 268 “semi-quantification” should be replaced with “semi quantitative”

Figure 5. The figure is difficult to read with different units plotted molec/cm3, mol/mol, ug/m3. I suggest that the authors stick to one unit: pptv. Given that the point of the figure is to look at the ratio between HCl and pCl this will make the figure more straightforward to read. Also, the panel on the right has 2 y axis with Cl(p) and none with HCl.

Text unclear as to whether the HBr values reported are upper or lower limits. Line 252 “lower limit estimates” while line 268 states “HBr concentrations should be treated as semi-quantification ones and upper limit values”.