Significantly reducing cigarette intake with the aid of NRT on a sustained basis may reduce harm and promote cessation (Moore et al., Reference Moore, Aveyard, Connock, Wang, Fryu-Smith and Barton2009; Beard et al., Reference Beard, McNeill, Aveyard, Fidler, Michie and West2011). It is therefore of interest to determine how reliable reductions can be attained. A substantial amount of the literature on health behaviour change points towards the utility of self-regulatory techniques (Michie, Abraham, Whittington, McAteer, & Gupta, Reference Michie, Abraham, Whittington, McAteer and Gupta2009; Michie, Hyder, Walia, & West, Reference Michie, Hyder, Walia and West2011; Helzer, Badger, Rose, Mongeon, & Searles, Reference Helzer, Badger, Rose, Mongeon and Searles2002; Quinn et al., Reference Quinn and Fromme2010; McAteer, Stone, Roberts, & Michie, Reference McAteer, Stone, Roberts and Michie2007; Becona & Vazquez, 2001; Barton, Blanchard, & Veazey, Reference Barton, Blanchard and Veazy1999). According to Control Theory this involves: (1) setting realistic goals, (2) reviewing these goals, (3) monitoring behaviour, (4) receiving feedback, and (5) intention formation (Carver & Scheier, 1981, Reference Carver and Schneier1982).
Smokers appear to find two of these techniques particularly difficult: the setting of attainable goals and monitoring performance (Sayette, Reference Sayette, Baumeister and Vohs2004; Beard, Vangeli, Michie, & West, in press). This is partially because cigarette consumption is an unreliable method of monitoring smoke intake. There is an extensive body of evidence that smokers often modify how they smoke their cigarettes, such as puff frequency, despite failing to reduce cigarette consumption (Beard, Fidler, & West, Reference Beard, Fidler and West2011; Beard et al., in press; Fagerstrom & Hughes, Reference Fagerström and Hughes2002). Smokers also fail to set difficult, realistic, and specific goals, which according to Goal Setting Theory is pivotal for optimal performance (Locke & Lantham, Reference Locke and Latham2004; Locke & Lantham, Reference Locke and Lantham1990; Abraham & Michie, Reference Abraham and Michie2008).
We examined whether providing smokers with a personal monitor for measuring expired-air CO concentrations, and a clear goal of maintaining smoke intake below 10 ppm at all times, would be a feasible method of achieving a reduction in smoke intake. CO is a colourless, odourless, and tasteless gas, that combines with haemoglobin in place of oxygen. It is one of the many compounds produced by cigarettes and appears to be a reliable measure of toxin intake (Middleton & Morice, Reference Middleton and Morice2000). Long-term exposure has been associated with a number of chronic conditions (e.g., Silverstein, Reference Silverstein1992; Cheng et al., Reference Cheng, Lyass, Massaro, O'Connor, Keaney and Vasan2010; Bye et al., Reference Bye, Sørhaug, Ceci, Høydal, Stølen, Heinrich and Wisløff2008). The development of portable CO monitors allows for the immediate assessment of toxin intake and is therefore a reliable method for self-monitoring.
Methods
Participants were recruited following participation in a study looking at the use of NRT for temporary abstinence and/or smoking reduction among those unable or unwilling to quit smoking (Beard et al., in press). Participants were given a CO monitor and asked to use it regularly throughout the day for 6 weeks, with the aim of maintaining their CO reading below 10 ppm (a threshold representing very light smoking). They were advised to use nicotine replacement therapy as well, but this was not provided. There are multiple CO monitors on the market. The one used in the current study is known as the COmpact™ Smokerlyzer® (Bedfont Scientific Ltd). This was chosen as it is small, easy to use, and is affordable to smokers. LEDs light up instantly on the screen using a familiar ‘traffic light’ system, which represents the level of carbon monoxide —Level 1 (green) 01–06 ppm, Level 2 (orange) 07–10 ppm, level 3 (red) 11–15 ppm, level 4 (red) 16–25 ppm, Level 5 (red) 26–35 ppm, Level 6 (red) 36–50 ppm, level 7 (flashing) 51–60 ppm.
At baseline, cigarette consumption, nicotine dependence, NRT use, past attempts to quit smoking, difficulty of these past attempts, motivation to quit and CO levels were recorded. Participants were also asked if they were currently attempting to reduce their cigarette consumption, if they had done so in the past, and if they ever modified how they smoked their cigarettes. Nicotine dependence was measured using time to first cigarette of the day (Fagerstrom, Reference Fagerström2003), while motivation to quit by asking: ‘Which of the following best describes you?’ (a) I really want to stop smoking and intend to in the next month, (b) I really want to stop smoking and intend to in the next 3 months, (c) I really want to stop smoking but I don't know when I will, (d) I want to stop smoking and hope to soon, (e) I want to stop smoking but haven't thought about when, (f) I think I should stop smoking but I don't really want to, (g) I don't want to stop smoking, (h) Don't know.
During the first 2 weeks, participants were instructed to record daily their cigarette consumption, usage of the CO monitor and NRT, average CO levels, and whether they had attempted to keep their reading below 10 ppm. Participants were also asked whether they found their CO monitor helpful and easy to use, and instructed to briefly explain why. At follow-up, baseline measures were repeated. Smokers were also asked whether they had attempted to quit smoking, if yes, how long the quit attempt had lasted, about their usage of the CO monitors in the previous 4 weeks, and to provide further details of their views and experiences of using the CO monitors for smoking reduction. Participants were paid £50 to cover expenses.
Analysis
T test analyses were used to determine whether there was a significant difference in cigarette consumption at baseline, during the first 2 weeks, and at the 6-week follow-up. Descriptive statistics are given for all other findings. Smoker' views about the use of CO monitors for smoking reduction were coded into six predetermined categories: (1) difficulties attaining a value of 10 ppm or lower, (2) difficulties using the monitor, (3) ease of use, (4) effect on cigarette consumption, (5) effect on motivation to quit and (6) reasons why they found the monitor helpful.
Results
Ten smokers were recruited; five females and five males, with an average age of 48.6 years (SD 11.56) and cigarette consumption of 14.1(SD 6.03) cigarettes per day. Two were retired, one unemployed and seven in full-time work. Seven smoked standard cigarettes and four rolled tobacco. Only two reported that they were currently using NRT. Three reported smoking within 5 minutes of wakening, three between 6 and 30 minutes of wakening, and 4 between 31 and 60 minutes of wakening. Two reported that they really wanted to stop smoking in the next month, seven that they really wanted to stop smoking but did not stipulate when, and one smoker that they didn't want to but thought they should. All ten had quit smoking at least once in the past for an average of 15.6 (SD 6.48) weeks, eight of which reported that they found it difficult to remain abstinent. Seven of the smokers were currently reducing their cigarette consumption and seven were modifying their smoking behaviour. Nine reported that they had attempted to cut down in the past. Two had a CO reading of 11–15 ppm, one 16–25 ppm, four 26–35ppm, two 36–50 ppm and one 51–60 ppm.
Four smokers used NRT during the first couple of weeks; only two on a regular basis. Over the course of the first 2 weeks, 79.3% (n = 111/140 responses) of participants reported that they found the CO monitor helpful, and 55.7% (n = 78/140 responses) reported that they found the monitor easy to use. Smokers used the monitor on average 2.9 (SD 1.49) times per day. Nine smokers completed the 4-week follow-up. During weeks 2 to 6, five smokers reported that they had used NRT. Four of the respondents had used their CO monitor daily during these 4 weeks; the other three had used their monitor around 3–4 times per week. Six of those followed up had attempted to keep their reading below level 2.
Eight smokers had peak daily CO concentrations below their baseline on at least 13 (92.9%) of the 14 days requiring daily monitoring. Three had CO levels below 10 ppm on 36% of the days, one on 21% of the days, and two on 7% of the days. Five smokers had CO levels below 15 ppm on at least 50% of the days. At the 6-week follow-up, all participants had CO concentrations below their baseline value; two were below 10 ppm and four below 15 ppm. Four had dropped 3–4 levels on the CO monitor from baseline, while five had dropped 1–2 levels. Over the six weeks there appeared to be a significant decline in the mean carbon monoxide score (r = 0.82, t = 5.36, df 14, p = 0.001; see Figure 1).
Figure 1 Graph of average Carbon Monoxide (CO) levels over time
Average daily cigarette consumption reduced from 14.1 (SD 6.03) at baseline to 9.8 (SD 4.95) during the two weeks of daily CO monitoring (t = 2.46, df 9, p = 0.036) and to 9.5 (SD 5.50) at 6-weeks follow up (t = 1.73, df 7, p = 0.127). Seven of the smokers reported that they felt as though the monitors had reduced their cigarette consumption and eight reported that they had modified how they smoked their cigarettes. Six smokers reported a lower nicotine dependency relative to baseline. Over the six weeks there appeared to be a significant decline in the number of cigarettes smoked per day (r = 0.81, t = 5.17, df 14, p = 0.001; see Figure 2). At follow-up, one participant had quit smoking. A further four smokers had attempted to quit smoking; one had quit for 2–4 weeks and three had quit smoking for 1–2 days. Three smokers reported that their motivation to stop had increased.
Figure 2 Graph of average cigarette consumption over time
Analysis of the statements provided by participants showed that many found it difficult to reduce their cigarette consumption so as to attain a CO value of less than 10 ppm (Theme 1). They also reported a number of difficulties with the monitors, including forgetting to use them (Theme 2.a), that they were difficult to carry (Theme 2.b), and initial problems with holding their breath for an adequate time prior to blowing into the monitor (Theme 2.c). Some of the smokers also reported that they found them embarrassing to use in public (Theme 2.d), that you need to first develop confidence in the monitor (Theme 2.e), and that the measurements were not accurate enough (Theme 2.f). Nevertheless, the monitors were deemed easy to use (Theme 3), increased motivation for smoking reduction (Theme 4.a), and resulted in reports of reduced cigarette consumption (Theme 4.b) and urges to smoke (Theme 4.d); as well as reports of modified smoking behaviour (Theme 4.c). A number of smokers also stated that the monitor had encouraged them to think about smoking cessation (Theme 5). The CO monitors were viewed to be helpful as they made smokers feel guilty about smoking (Theme 6.a); were rewarding (Theme 6.b); allowed comparisons between times when they did and didn't smoke (Theme 6.c); and picked up the effect of environmental smoke (Theme 6.d). Smokers also reported that it made them more aware of the effects of smoking on their body (Theme 6.e), demonstrated that their CO consumption was higher than anticipated (Theme 6.f), indicated the amount of smoke inhaled from each cigarette (Theme 6.g), and provided a picture of the effect of NRT on cigarette consumption (Theme 6.h; See Table 1).
Table 1 Smokers Views and Beliefs on the Use of Carbon Monoxide Monitors for Smoking Reduction
Discussion
This study examined whether providing smokers with a personal monitor for measuring expired-air CO with the specific goal to reduce CO levels below 10 ppm, would be a feasible method of achieving a reduction in smoke intake. Although the majority of smokers failed to keep their average daily CO concentrations below 10 ppm, average readings were below their baseline levels. Average daily cigarette consumption and nicotine dependency also reduced from baseline to follow-up. Use of the CO monitors was found to be acceptable and to increase motivation to stop smoking, with half of participants reporting an attempt to quit smoking.
Previous studies have detailed the problems smokers experience in regulating their intake (Sayette, Reference Sayette, Baumeister and Vohs2004; Beard, Vangeli, Michie, & West, in press). The results here not only suggest that using CO monitors and the setting of specific goals may eliminate these issue, but that it could be a reliable method for reducing smokers’ toxin intake and increasing motivation to stop completely. This is despite low levels of NRT use. As smoking reduction with NRT is superior to reduction without pharmacological help, it may be anticipated that even greater benefits may be attained if smokers are actively encouraged to use medicinal nicotine (Moore et al., Reference Moore, Aveyard, Connock, Wang, Fryu-Smith and Barton2009; Beard et al., Reference Beard, McNeill, Aveyard, Fidler, Michie and West2011). A controlled trial with long-term follow-up is warranted to further assess the implications of using CO monitors for self-regulation of smoking behaviour.
Conclusions
Regular personal CO monitoring with the specific goal to reduce smoking below 10 ppm may be a useful method for reducing smokers’ intake of smoke and increasing their motivation to stop completely.
Acknowledgments
This study was funded by Cancer Research UK. The CO monitors were provided by Bedfont Scientific Ltd (http://www.bedfont.com/).
