I have always wondered what is the relationship between PM2.5 measurement and humidity/dew point. From what I have read all three types of PM2.5 sensors (beta r

I have always wondered what is the relationship between PM2.5 measurement and humidity/dew point. From what I have read all three types of PM2.5 sensors (beta ray, particle counting...) can't tell the difference between dust particles and water droplet. Googling around gives me a lot of conflicted answer[1][2][3]. If one looks at the air quality graph of my city[0], it can be seen that summer has much better AQI while winter/spring are worse. But I feel summer is much more dustier and spring is cleaner because the street is always wet from drizzle (dust is prevented from floating in the air). Maybe it has something to do with the lower dew point during winter/spring as my city has very high humidity, from 60% to 100% (right now it is 90%). [0] http://hanoiair.de/en_US/ http://hanoiair.de/en_US/ [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4555266/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4555266/ [2] https://www.ncbi.nlm.nih.gov/pubmed/29063278 https://www.ncbi.nlm.nih.gov/pubmed/29063278 [3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4072227/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4072227/