Characterization of Mainstream Cigarette Smoke Particle Size Distributions from Commercial Cigarettes Using a DMS500 Fast Particulate Spectrometer and Smoking Cycle Simulator

Particle size distribution and number concentration measurements of mainstream cigarette smoke are reported for commercial cigarettes encompassing a broad range of design parameters. Measurements were made using a Cambustion DMS500 fast particulate spectrometer. Twenty-nine brand styles were evaluated using a 60-mL puff of 2-s duration taken once every 30 s. A subset of cigarettes was evaluated using additional smoking regimens to explore the influence of puff volume and filter ventilation blocking. The DMS500-derived particulate matter mass was compared with filter-collected mass to assess the reliability of the aerosol measurements. Under the 60-mL/2-s puffing condition, all puffs for all products were observed to exhibit count median diameters between 145 nm and 189 nm. Measured particle size was 12-22 nm smaller for a 60-mL puff relative to a 35-mL puff. Partial or complete filter ventilation blocking under the 60-mL/2-s puffing condition had a small effect on particle size. Some trends in particle size as a function of puff number and smoking regimen appear consistent with a tobacco-rod residence time/coagulation hypothesis; however, other observations suggest that smoke formation processes in addition to coagulation influence particle size. The DMS500 underestimates smoke particulate mass relative to gravimetric filter collection, indicating evaporation of cigarette smoke particulate matter within the instrument. Approximately 75% of the evaporated mass can be attributed to particulate phase water. Some data also suggest a possible underestimation of number concentration. This introduces a significant confounding bias in the measurements and limits the information on smoke formation that can be extracted.