Dear Authors,

I apologize for not being able to handle the reviewing process earlier.

I believe you provided satisfactory answers to the issues raised by both reviewers in this new version of the manuscript.

considering the AMT discussion and to finalize the manuscript, I would simply ask whether you would consider revising the last sentences in your conclusions in order to make a stronger statement on the need for calibration for these low-cost sensors.
for example, should the sentence "Overall, we conclude that the Plantower PMS3003 sensors, as a promising low-cost PM monitor, can achieve high accuracy
and precision over a wide range in PM2.5 concentration, but only after applying appropriate calibration" be turned into "Appropriate calibration is required to achieve the required level of accuracy and precision over a wide range in PM2.5 concentration needed for monitoring PM2,5 with Plantower PMS3003 sensors". Same for the next sentence in some ways : "is ONLY feasible with current low-cost sensing technology if proper calibrations is performed..." It basically says the same but I am afraid that considerations on the need for adequate traceability of calibration / RH adjustments will be lost somewhere in the process and that your paper may be only considered as a validation of sensor's performances for PM monitoring. Conditions for reaching the expected performances should not be seen as optional, especially when large cities in emerging countries are consiring the use of such sensors for their air quality operational framework.

Dear authors,

many thanks for the last changes,

Regards,

Paolo Laj