[J_cst]

Thank you for your references. The second one has little to do with the subject though. The first one confirms that "This did, indeed, block a little tar and toxic gas, but smokers, ever resourceful, responded by changing their behavior—smoking more, taking deeper puffs, etc—thereby making the practical effect of the cellulose-acetate filter approximately nil". This by the way, is what happens in the napkin "experiment" I was referring to. By the way, I just learnt that what I was calling a "filter", it is not a filter, but a mixer.[0]

TL;DR: It's a device whose purpose is to mix the smoke of the cigarette with air which is intaken via the micro holes found on the body of the mixer (a.k.a. "filter). The different air/smoke mix rates give the smoker a different perception of the smoothness / lightness of the cigarette. As a side note, as your first reference mentions, this "filter novelty" may have made things worst as the smoker will make deeper breaths and keep the smoke longer into the lungs when inhaling a more diluted smoke puff.

[0] https://www.theatlantic.com/health/archive/2017/07/cigarette...

[gumby]

The second ref was as support that the "filter"s are also bad for you in their own right but provide a "benefit halo" that helps support smoking, just as the tobacco companies intended.

[J_cst]

Thank you