Factors affecting filter tip colour as a measure of mouth level exposure to tobacco smoke constituents
The purpose of this investigation was to evaluate the potential effects of puffing regimen, storage time and temperature on filter tip colour and yields in relation to yields of tar, nicotine and CO. Ten brands of Canadian cigarettes, 2 with taped filters, were smoked using a full 34 factorial design (81 smoking regimens; puff volume, 25, 50, 75 mL; puff duration, 1.5, 1.5, 3.5 s; puff interval, 30, 60, 90 s; and butt length filter+overwrap+ 3, 6, or 9 mm). Yields of tar, nicotine, CO were determined and filter colour measurements made immediately after smoking and after 24, and 168 hours storage at room temperature or -10 °C. Filter colour measurements (CIE L*, a* and b*) were obtained from the end of the filter closest to the tobacco column (rod end) using a Macbeth Color-Eye 2020+ with a 4 mm diameter aperture and D65 (average north sky daylight) illumination. Averaged values for L* and a* values were found to be logarithmically related to the tar yield but the relationship with b* was linear. There were highly significant changes in values for L* a* and b* with time when filters were kept at 20 °C which were dramatically reduced by freezing. After 1 week at -10 °C, only a slight increase in yellowness and decrease in redness was noted. With respect to tar yields, the effect of changes in puff interval and puff duration were virtually identical but less than that of puff volume. Moving from a 90 s interval to a 30 s interval or decreasing the puff duration from 3.5 seconds to 1.5 seconds both resulted in an increase in tar yield of approximately 5 mg/cig. Butt length was the least significant factor. Decreasing the butt length from 9 mm to 3mm increased tar yield by about 3 mg/cig.