Hi. subir here from Pune, India.
We have been developing some low cost openhardware for PM measurements and have good amount of data over the past 6-7 months over 5 locations in our city. When compared to government published PM data, our values approximately match government values during colder days than during hotter days. This observation is seen repeatedly and consistently and is especially significant (20-30 ug/m3 difference) now during the hot summer months.
Our system uses Sensirion's SPS30 sensors for PM measurements and Bosch's BME280 for ambient temperature and RH.
I would like to know if we need to cool the air we sample to steady the air sample temperatures to a constant value for consistent results? Anyone who does this on their low-cost systems? Should we also worry about removing moisture?