The authors addressed all my concerns and I have no further comment.

This is a nice study that analyzes the effect of seesaw transport and stagnation days on local PM2.5 pollution in several regions of China and the health impact of PM2.5 pollution. The authors should have spent great efforts on presenting comprehensive results. This paper is well-written, and I recommend it for publication after consideration of the points below.

Comments

L149-150 The authors should clarify if they are simulating only DJF or all 2014-2019 period. Related to WRF, would be a nice addition to know if they are using nudging or daily initialization of meteorology and what’s the length of the spinup period.

Throughout the manuscript, please make clear that you are referring to the DJF period. Sometimes,  in the manuscript it is written “2014-2019” and Figure’s caption refers to winter 2014-2019

At times difficult to read, i.e. L270-287. Please explain if “day 1” represents the mean of all days considered as the first day of all 24 events or if the authors are referring to a specific event.  If the authors are talking about the mean, have they verified the dominant wind direction for each event?

L363 Fig 6a doesn’t show a clear positive trend for PM2.5 and HSR