Aerodynamic sizing of tobacco smoke particulate from commercial cigarettes.

Aerodynamic sizing of smoke particulate was performed on a variety of commercial cigarettes using a single particle aerodynamic relaxation time (SPART) analyzer. Cigarettes tested were rated as "medium," "low," or "ultra-low" tar by the Federal Trade Commission method. Aerodynamic size determinations were made with filters attached and with filters removed. Smoke particles from all cigarettes were less than 0.6 micron mass median aerodynamic diameter, and particle size was not affected by filters. Commercial filters reduced particle number concentration by 20-96%. Particle number concentration of smoke particles from some "low" tar cigarettes was found to be similar to some "medium" tar cigarettes. Particle number per puff increased as the cigarette shortened. These findings suggest that estimation of tar delivery to smokers from cigarettes should include puff number information. Also, the ultimate respiratory tract deposition site of smoke particles is not affected by filters since particle size was not altered by passing smoke through cigarette filters.