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Blocking Filter Vents Increases Carbon Monoxide Levels From Ultralight, But Not Light Cigarettes

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Abstract

Effect of vent blocking on carbon monoxide (CO) exposure from a best-selling light cigarette was examined in 12 daily cigarette smokers. Mean CO boosts were not different from each other with (a) 0% filter vents blocked (5.0 ppm), (b) vents covered with lips (4.9 ppm), (c) 50% of vents covered with tape (4.8 ppm), and (d) vents covered with a pinch of the fingertips (4.9 ppm). A second study in another 12 smokers was conducted to replicate these findings as well as earlier findings that blocking vents doubles CO intake from 1-mg tar cigarettes. While blocking half the vents with fingers significantly increased CO boost from ultralight cigarettes (2.8 vs. 5.4 ppm, p < 0.001), it did not influence boosts from light cigarettes (6.3 vs. 6.5 ppm, p = 0.8). The lowest yield cigarettes (1 mg tar) may be special. Smoking machine simulations provide poor models of human smoke intake. It is unclear whether tar and nicotine intake from light cigarettes was influenced by vent blocking.

Section snippets

Participants

Twelve cigarette smokers (seven women and five men) were recruited through fliers and newspaper advertisements. The average participant was 21 years old (range 20–24, SD = 1.0), smoked 21 cigarettes per day (range 10–30, SD = 5.0), and had been smoking regularly for 6.5 years (range 2–12, SD = 2.4). Three participants reported their usual brand as being Marlboro Lights, three Marlboro Full-Flavor, two Parliament Lights, one Marlboro Medium, one Sebring Full-Flavor, one Newport Full-Flavor, and

Results—study 1

Mean pretrial CO readings were 25.0 ppm (SE = 3.8), 26.4 ppm (SE = 3.5), 24.8 ppm (SE = 3.9), and 25.8 ppm (SE = 3.8) for the unblocked, lip-blocked, tape-blocked, and finger-blocked conditions, respectively, F(3, 33) = 0.52, NS. There was, therefore, no reason to expect that pretrial CO readings would influence the CO boosts for the four conditions. Mean CO boosts for the unblocked, lip-blocked, tape-blocked, and finger-blocked conditions were remarkably similar: 5.0 ppm (SE = 0.47), 4.9 ppm

Discussion—study 1

The results of Study 1 suggest that blocking the filter vents on a 10-mg tar cigarette (i.e., a “light” cigarette) has no added effect on smoke exposure in human smokers, as measured by expired air CO levels. It should be noted that the exact placement of the filter vents can vary from cigarette to cigarette, but their location generally ranges from 12–15 mm from the proximal end of the cigarette. Individual differences in smoking behavior on CO levels were minimized in this study by employing

Study 2

The purpose of Study 2 was to attempt to replicate the findings of both Study 1 and previous work done with ultralight cigarettes [12], while at the same time allowing for direct experimental comparisons between ultralight and light cigarettes. We also wanted to examine an additional vent blocking maneuver not previously studied with ultralight cigarettes (i.e., finger blocking).

Participants

Twelve cigarette smokers (six women and six men) were recruited through fliers posted around the Penn State campus. The average participant was 23 years old (range 20–29, SD = 3.0), smoked 22 cigarettes per day (range 10–45, SD = 10.0), and had been smoking regularly for 7.4 years (range 2.5–15, SD = 4.7). Three participants reported that they usually smoked Marlboro Lights, two Camel Lights, two Camel Filters, one Marlboro Full-Flavor, one Marlboro Medium, one Parliament Lights, one Merit

Results—study 2

Average pretrial expired air CO levels were similar across the four experimental conditions: 25.4 ppm (SE = 3.1), 25.4 ppm (SE = 1.9), 24.9 ppm (SE = 2.5), and 24.8 ppm (SE = 3.0) for the ultralight unblocked, ultralight finger-blocked, light unblocked, and light finger-blocked conditions, respectively, F(1, 11) = 0.001, NS. There was, therefore, no reason to expect that pretrial CO readings would influence the CO boosts for the four conditions.

Both cigarette and blocking main effects were

Discussion—study 2

The CO boost results from Study 2 replicate quite well both those results from Study 1 with light cigarettes and those results previously obtained using ultralight cigarettes [12]. While covering half the filter vents on a 1-mg tar cigarette results in a doubling of CO exposure, the same manipulation with a light cigarette appears to have no effect on CO exposure in human smokers. Several of the trends that did not reach an acceptable level of significance according to the adjusted Bonferroni

General discussion

Since the early 1980s, researchers have been well aware of the discrepancy between advertised cigarette yields, as determined by standard smoking machine assays, and smoke exposure levels in human smokers [3]. This discrepancy has been attributed to people smoking more intensively than smoking machines. They generally take a greater number of higher volume puffs in shorter intervals of time than is specified by smoking machine parameters. In an attempt to reduce this discrepancy and thereby

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