Measurement of exhaled breath carbon monoxide in clinical practice: A study of levels in Central Pennsylvania community members

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Exhaled breath carbon monoxide (eBCO) is easily measured and can be a predictor of health outcomes, even after controlling for self‐reported smoking status (Berard et al., 2015). Carbon monoxide (CO) is a colorless, odorless, poisonous gas that cannot be detected without the aid of a device. Measurement of eBCO is noninvasive and practical for clinical use (Wheeler‐Martin et al., 2015). CO is a common contaminant of outdoor and indoor air, and thus ambient levels of CO should be considered when measuring eBCO particularly in the nonsmoking population where one would expect the levels to be low (Ryter & Choi, 2013).
eBCO is used frequently as a measure of smoking status in tobacco treatment programs and research studies (Cropsey et al., 2014; Javors, Hatch, & Lamb, 2005). The American Association of Nurse Practitioners (2016) urges regular cancer screenings, and nurse practitioners can use this measure to screen for potential cancer risks, such as lung, oral, or cervical cancer, and bring attention to the risk of smoking in causing chronic conditions such as chronic obstructive pulmonary disease (COPD), emphysema, and chronic bronchitis (Molinari et al., 2015). Although a 2012 Cochrane review does not support the use of eBCO as a biomedical measurement used to increase cessation rates (Bize et al., 2012), eBCO is a method of teaching about the effects of smoking on the body, and nurse practitioner assessed eBCO provides useful biomedical information to smokers embarking on a quit attempt (Foulds et al., 2015).
Most CO exposure comes from inhaling smoke, and eBCO levels are typically increased in smokers relative to nonsmokers (Deveci, Deveci, Acik, & Ozan, 2004). Readings ≥10 ppm are usually confirmatory of current smoking regardless of self‐report status. In 2002, The Society for Research on Nicotine and Tobacco sets the eBCO cutpoint to confirm self‐reported abstinence from smoking as eBCO < 10 ppm (Benowitz et al., 2002), as did Jarvis et al. in 1987 (Foulds et al., 1997; Jarvis, Tunstall‐Pedoe, Feyerabend, Vesey, & Saloojee, 1987). However, recent literature has recommended the cutpoint much lower at eBCO < 7 ppm (Stelmach et al., 2015) and <5 ppm (Cropsey et al., 2014). This controversy over the correct eBCO cutpoint to be used to confirm abstinence from combustible tobacco use (Cropsey et al., 2014; Javors et al., 2005) makes it difficult for the healthcare provider to know which number to use when validating smoking status.
An explanation of the recent decrease in expected eBCO in a nonsmoker is likely because of the advent of tobacco control legislation in response to the 1990 Federal Clean Air act amendment. Since the enactment of Pennsylvania's Clean Indoor Air Act in 2008, which prohibits smoking in a public place or a workplace that does not have legally approved exemptions, the level of secondhand smoke exposure has dropped (Commonwealth of Pennsylvania, 2008). In 2014, the U.S. Centers for Disease Control and Prevention (CDC) stated that “Eliminating exposure to secondhand smoke and promoting cessation are two evidence‐based strategies cited that can contribute to a reduction in disease, disability and death related to tobacco use and secondhand smoke exposure” (Centers for Disease Control and Prevention, 2007).
Many reports and studies consistently document reductions in tobacco use following the implementation of smoke‐free laws and policies (Commonwealth of Pennsylvania, 2008). In the European Union, a cross‐sectional study measuring eBCO among nonsmokers was used to measure the strength of tobacco control policies, and the effect on secondhand smoke exposure. It was found that eBCO decreased with increased strength of tobacco control policies (Tual, Piau, Jarvis, Dautzenberg, & Annesi‐Maesano, 2010).
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