Interesting product with unique strengths and limitations. Well described, thanks for uisng ESSD.

Small additional fixes or suggestions. Some of these might emerge from proofreading but better that you control the corrections beforehand.

1) Fix text at lines 102, 103;
2) Line 152: lower, vs lowering?
3) Line 162, MOTE Ltd: instrument manufacturer, environmental consulting company?
4) Line 174: plantower?
5) Line 174: Do you need to indicate SHT sensors as based on Sensirion?
6) Line 208: Because I, many friends, and likely many northern hemisphere readers worked with and know US-based UNIDATA, please follow reviewer advice and include Aussie Unidata url here, at first use.
7) Line 254: an not and?
8) Line 280: MOTE here indicates a project, company, ministry, ?
9) Line 281: Not clear what your regression provides? You regress PM concentrations vs location? Vs met variable (T, RH)? Modeled vs measured? Site to site correlation?
10) Line 303: But you earlier implied that exceedence values of PM came from residential heating using solid fuel (wood, coal) sources. Quantifying / modeling PM concentrations across the city requires knowing advective inputs plus local production? Fixed sites already provided sufficient local information?
11) Line 314 - but earlier (line 255) you told us that ceilometer data were “incomplete”?
12) Line 315 - where vs were? So ceilometer only raw, not QC’d. Why not leave them out? In fact, you never discuss them. Not useful?
13) Line 429 - missing ‘)’ here?
14) Line 445 - calculation of full uncertainty budgets (e.g. instrumental, operational, environmental) rarely comes out as simple as reference - measured. As subsequent discussion in this paragraph proves!
15) Line 495 - you mean not the same meteorological or trajectory source air, but air containing the same particle concentrations and size distributions?

Thank you for fast response and thank you for using ESSD!