The Effect of Tip Dilution on the Filtration Efficiency of Upstream and Downstream Segments of Cigarette Filters

The amount of particulate matter captured by the upstream and downstream segments of ventilated filters was directly determined by a UV method. With 25 mm 3.3 dpf/35000 total denier filters the dry particulate matter efficiency of the upstream section approximately doubled and the nicotine efficiency increased by about a half in going from 0 to 70 % tip ventilation. The efficiency of the downstream segment showed only minor variations. This resulted in an increase of total filtration efficiency from 48 % to 63 % for dry particulate matter and from 40 % to 49 % for nicotine. The dry particulate matter/nicotine ratio decreased from about 15 for non-ventilated cigarettes to less than 10 at 70 % tip ventilation because the tobacco column produced smoke containing relatively more nicotine and the difference between dry particulate matter and nicotine filtration efficiencies became successively larger as ventilation increased.