According to marketing materials posted on Stanford.edu, Parliament cigarettes have recessed filters so that only the flavor of the tobacco touches your lips. This may lead a smoker to believe that no other toxic chemicals or additives come in contact with the body, making Parliaments a "healthier" cigarette.
In actuality, the recessed filters found on Parliament cigarettes are nothing more than a gimmick to sell more cigarettes, according to the Stanford post. Filters, whether recessed or full-length, do very little to reduce the harmful effects of smoking. Most scientists agree that smokers inhale the same amount of toxic material whether or not their cigarettes are filtered. However, marketing agencies used the idea of filters to sell a supposedly healthier cigarette to "smarter" smokers.