Current public health guidelines on the identification and treatment of smokers and the information on the health risks associated with tobacco are based on studies that focus on adult daily cigarette users (1). Daily smoking, however, is declining and light and intermittent smoking are increasing (2, 3). Light and intermittent smoking are frequently found among the young, the educated, women, (4, 5) and minority populations (Hispanics/Latinos, African Americans, American Indians, Alaska Natives, Asian Americans, and Pacific Islanders (6–9)). Light and intermittent smokers pose a serious challenge to health care professionals because they tend not to consider themselves “smokers” and, consequently, are under-identified (10–13). This propensity not to label oneself as a smoker reinforces the belief that light and intermittent smoking does not carry significant health risks.
There is not a consensus on how to best define “light smoking” (7, 12, 14). Light smokers have been classified as smoking less than 1 pack/day, less than 15 cig/day, less than 10 cig/day, and smoking 1–39 cig/week (9, 14). There are various subgroups of light smokers: low-rate daily smoking (fewer than 5 cig/day) (15), very light smoking (fewer than 6 cig/day) (14, 16), and “chippers” who consistently smoke no more than 5 cig/day on the days when they do smoke (17). In the past, light smoking has been viewed as a transient practice among former heavier smokers or among tobacco users who are trying to quit (4, 5, 18). New research, however, shows that some light smokers maintain this consumption pattern indefinitely (11, 12, 19).
Like light smoking, intermittent smoking is a broad term that consists of a variety of patterns of tobacco use but is generally defined as smoking on a nondaily basis (4–6, 8, 12, 14, 20–22). Social smoking is another example of intermittent smoking, which is characterized by limiting smoking to social contexts, such as parties, bars or nightclubs (11, 12). (Social smokers, unlike other types of intermittent smokers, may never smoke alone (11, 23)). As with light smoking, intermittent smoking is common among minority populations (4, 5, 8). African American smokers are nearly twice as likely to smoke intermittently (OR 1.82, 95% CI 1.59–2.07) and Hispanic/Latino smokers are three times more likely to smoke intermittently (OR 3.2, 95% CI 2.75–3.74) than non-Hispanic Whites (6). Among young adults, intermittent smoking is frequently paired with excessive alcohol use, particularly binge drinking, on US college campuses (24, 25).
The number of young adult smokers (age 18–29) who consume less than 5 cig/day has increased from 4.7% in 1992 to 6.0% in 2002 (3). According to the 2002 National Survey on Drug Use and Health, over one third of all adult smokers report smoking less than daily (26). The 2007 Behavioral Risk Factor Surveillance Survey data indicate that 26% of adult smokers were nondaily smokers (2). The prevalence estimates of light and intermittent smoking are likely an underestimate because most surveys rely on self-report measures and nondaily smokers tend to self-classify as nonsmokers (10–13). This important change in the composition of the US smoking population has developed in part because of tobacco control policies, including home and workplace smoking restrictions, coupled with society’s progressive de-normalization of smoking (3, 12, 13).
As smoking patterns continue to change, there will be a shift in the US smoking population from daily, addicted tobacco users who smoke for the clear physiologic and psychological benefits of nicotine to the low-level or occasional smoker who may not suffer from the same degree of nicotine dependence (12). Understanding the health effects of light and intermittent smoking is important for healthcare professionals who are increasingly likely to encounter this type of tobacco use in practice. While the available literature is not large, it indicates that light and intermittent smoking pose substantial risks; the adverse health outcomes parallel dangers observed among daily smoking, particularly for cardiovascular disease.