Prevalence and correlates of secondhand smoke exposure in the home and in a vehicle among youth in the United States
Introduction
Exposure to secondhand smoke (SHS) causes significant disease and death, including ear infections, more frequent and severe asthma attacks, respiratory infections, and Sudden Infant Death Syndrome among infants and children (US Department of Health and Human Services, 2014a; US Department of Health and Human Services, 2014b). Over the past two decades, an increasing number of states and localities have implemented comprehensive smoke-free policies prohibiting smoking in public places, including all indoor areas of worksites, restaurants, and bars (Centers for Disease Control and Prevention, 2011; Tynan et al., 2016). As of December 2017, the proportion of the U.S. population protected by a comprehensive state or local smoke-free law was nearly 60% (Tynan et al., 2016), and marked declines have occurred in population level SHS exposure (Centers for Disease Control and Prevention, 2010; Homa et al., 2015; McIntire et al., 2014).
Despite this progress in reducing SHS exposure in indoor public places, private settings such as the home and family vehicle still remain as primary sources of SHS exposure, especially among youth (Centers for Disease Control and Prevention, 2010; US Department of Health and Human Services, 2006). Children generally spend more time at home and in other private settings than elsewhere; for example, only about 14% of total hours in a year are spent within the school environment among U.S. youth enrolled in public schools (National Center for Education Statistics et al., 2008). However, children and youth have limited control over their own exposures to SHS within such private settings. The extent of SHS exposure among this population might be increased by the relatively confined nature of private spaces and the longer durations of exposure (US Department of Health and Human Services, 2006; US Department of Health and Human Services and US Department of Health and Human Services, 2010). Exposure can be particularly high in enclosed environments such as vehicles; a previous study demonstrated that smoking in a car yields unsafe levels of SHS contaminants such as fine particulate matter (PM2.5), carbon monoxide (CO), and nicotine, especially for children, even under realistic ventilation conditions (Sendzik et al., 2009; Rees and Connolly, 2006; Semple et al., 2012; Vardavas et al., 2006). Another study found that the average level of polycyclic aromatic hydrocarbons (PAH), a by-product of burning tobacco products, is markedly higher in vehicles than in enclosed public places such as bars and restaurants (Northcross et al., 2014).
A basis for concern about SHS in children is the negative effect of such exposure on their health. Neurotoxic substances such as lead, arsenic, and several other heavy metals are present in SHS, and could potentially impair cognitive development and functioning in children (US Department of Health and Human Services, 2006). Other SHS-attributable conditions in children such as respiratory infections, ear infections, and asthma attacks (US Department of Health and Human Services, 2006) could require outpatient visits or hospitalizations, potentially contributing to school absenteeism. Although most US households reported having smoke-free home rules (80.3% in 2010–2011), millions of youth still are exposed to SHS in private areas. Poor enforcement of voluntary smoke-free rules, coupled with SHS incursion from neighboring units, could result in involuntary SHS exposure among infants and children (Centers for Disease Control and Prevention, 2010; Homa et al., 2015).
There is paucity of recent, nationally representative surveillance data on extent of exposure to SHS among youth within the home and in a vehicle. Despite the fact that the U.S. tobacco product landscape has diversified to include emerging combustible and electronic products (US Department of Health and Human Services, 2012; US Department of Health and Human Services, 2016), conventional cigarettes and other combustible products are still commonly used by U.S. adults overall, including parents living with their dependents (Wang et al., 2018; Agaku et al., n.d.). Thus, timely surveillance data is critical to inform tobacco prevention and control programs aimed at protecting youth from involuntary SHS. To address this gap, this study measured youth exposures to home and vehicle SHS, and explored correlates of exposure among youth using data from the 2016 National Youth Tobacco Survey (NYTS) among U.S. 6th–12th graders.
Section snippets
Data source, target population, and sampling
NYTS is a nationally representative, school-based, paper-and-pencil survey of U.S. middle (grades 6–8) and high (grades 9–12) school students attending both public and private schools (Centers for Disease Control and Prevention, n.d.-a). A three-stage cluster sampling procedure (county, school, and class) was used to generate a probability sample; a total of 20,675 eligible students completed the 2016 NYTS, yielding an overall response rate of 71.6%. The NYTS sampling frame excluded schools
Results
Among U.S. middle and high school students in 2016, 50.6% were male, 55.8% were in high school, and 52.3% were non-Hispanic white. Overall, 13.2% reported past 30-day use of any tobacco product, and 9.0% reported past 30-day use of any combustible tobacco product.
Discussion
During 2016, nearly one-third of U.S. youth (7.50 million) reported being exposed to SHS in the past week in either the home or vehicle. The perception that SHS is harmful was not protective against SHS exposure, possibly because youth have very little control over their exposures in these private environments (Centers for Disease Control and Prevention, 2010; US Department of Health and Human Services, 2006); for example, they may not be able to physically remove themselves from places where
Conclusion
Nearly one-third of U.S. youth were exposed to either home or vehicle SHS. Among non-tobacco-using youth with tobacco-using household member(s), the home was a dominant SHS exposure source; among tobacco-using youth with non-tobacco-using household member(s), a vehicle was a dominant exposure source, possibly peers'. Comprehensive smoke-free laws, coupled with fully enforced smoke-free home/vehicle rules and population-level education about the harms of SHS exposure, can reduce youth exposure
Financial disclosure
The authors have no financial relationships relevant to this manuscript to disclose.
Funding source
There was no external funding for this manuscript.
Table of contents summary
This study assessed prevalence and correlates of vehicle and home secondhand smoke (SHS) exposure among U.S. middle and high school students during 2016.
Contributors' statements
Dr. Agaku conceptualized and designed the study and drafted the initial manuscript.
Ms. Odani helped conceptualize the study, assisted in the statistical analyses and critically reviewed and revised the manuscript.
Dr. Armour and Dr. King helped conceptualize the study and critically reviewed and revised the manuscript.
All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
Disclaimer
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the U.S. Centers for Disease Control and Prevention.
Declaration of Competing Interest
The authors have no conflicts of interest to disclose.
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