For cig smoke like the thin stuff, you may get away with faster renders and not using any density at all, just adjust the emission channel, but feed it correctly, see my image, tweaking a rgb curve right
There may also be important racial differences, with African Americans, particularly females, having a higher risk than white smokers (Dransfield et al., 2006
Marynak KL, Wang TW, King BA, Agaku IT, Reimels EA, Gaffunder CM
Most viruses utilized as biological building blocks are plant or bacterial viruses of either spherical (quasi-icosahedral) or fiber/rod shape (helical symmetry), with the application perspectives differing in certain aspects for these two types of backbones (as illustrated in Figure 3 and some review articles [6,71,72])