Settling by gravitation depends on mass and thus on density, but that's a relatively minor loss process at least for submicron aerosol. (realclimate.org)
Saarikoski, S., Timonen, H. Carbone, S., Kuuluvainen, H., Niemi, J. V., Kousa, A., Rönkkö, T., Worsnop, D., Hillamo, R. & Pirjola, L.: Investigating the chemical species in submicron particles emitted by city buses, Aerosol Sci. (en.ilmatieteenlaitos.fi)
Using submicron synchrotron x-ray beam, a group of scientists led by the Geophysical Laboratory's Ho - kwang «Dave» Mao, have studied the loading behavior of the DAC up to 400 GPa. (gl.ciw.edu)