Dear Authors,

Thank you for the revision of your manuscript. After convening with one of the reviewers, I have only one minor suggested revision given below before proceeding to the next step of publishing your manuscript.

With kindest regards,

Daniel Knopf

Minor revisions:
This concerns text on lines 262-275:
The sentence starting on line 265 "The phenomenon...". This is a confusing statement. You mean that this result occurs because not all chemical species are well constrained? This needs a bit more elaboration, so the reader can understand this.
This other point is: It seems that you refer to a study reporting lower organic fraction at high PM2.5, but in that case, one of the reviewer believes that the inorganic fraction is increased. It thus cannot explain the decrease of the inorganic fraction here. Could you please explain the reasons for the reduced inorganic fraction and what other chemical compounds (e.g., dust particle) may contribute to that.

Dear Authors,

Thank you for the revision of your manuscript. I am happy to accept your manuscript as article in Atmospheric Chemistry and Physics.

With kindest regards,

Daniel Knopf