Keep in mind that the High Efficiency + Activated Carbon filters capture not just cigarette smells, but even odors, Formaldehyde, and everything that High Efficiency filters capture (smoke, pet hair, viruses, pollen, allergens, dust, PM2.5, etc)
Change it sooner after heavy smoke
Closed systems are those that cannot be taken apart, have the tank refilled, or be altered by the user
(Fun fact: Smoking menthol cigarettes does tend to feel smoother because the substance has a numbing effect on the throat and lungs, inhibiting the bodys ability to signal irritation to the brain.) Smokers were urged to switch to Kools to give their throats a break from the harshness of regular cigarettes, or to treat themselves when suffering a case of the sniffles