Tobacco use continues to be a primary global health issue, with over 180 nations committed to reducing smoking as signatories to the Framework Convention on Tobacco Control . Cigarette smokers have shorter lifespans than non-smokers by at least 10 years , due to many health issues, including cancer, cardiovascular diseases, and respiratory diseases . The negative effects of cigarette smoking are large and well-documented for most countries. In the United States, more people have been prematurely killed by cigarette smoke than in all of the nation’s wars combined . In the United Kingdom, 19% of cancer cases are linked with exposure to cigarette smoke . And in China, alone, approximately one million deaths are linked to cigarette smoke each year . Globally, tobacco kills more than six million people each year .
These impacts are distributed unequally, with consequent inequities. For this work, we adapt a definition of inequalities as ‘the different availability of resources to which individuals and groups have access to’ . A range of studies have found evidence of inequities in tobacco smoking and secondhand smoke (SHS) exposure [5, 7, 8], with minorities generally experiencing higher risks related to tobacco. Research in the United States revealed differences in likelihood of smoking by ethnicity, which became larger with age . Another study in the United States found that smokefree home policies were more prevalent in the West, and among those making over $100,000 and those with graduate degrees . A study in the Southeastern United States found that less-educated citizens were less likely to be covered by smokefree space policies, and that smoking was a predictor of dropping out of high school . In addition to ethnic differences, the likelihood of tobacco addiction has been associated with educational attainment, socioeconomic status, and region [5, 11,12,13]. In a study of American twins in the military, cigarette smoking was found to have an association with lower educational attainment . Geographically, in the United States in 2015 the Midwest had the highest prevalence of cigarettes smoking among adults 18 years and older at 18.7%, above the national prevalence of 15.1%, and the southeastern states of West Virginia and Kentucky had prevalences of 26.7 and 26.2%, respectively . These inequities in smoking prevalences by ethnicity, socioeconomic status, and geography suggest drastically different tobacco related risks within America, dependent on circumstances and experience. To counter this, more widespread policies to cover vulnerable populations are needed.
Research has consistently found that denormalizing smoking is an effective way of decreasing smoking prevalence and preventing initial uptake of tobacco use [14,15,16,17]. To denormalize smoking is to reduce its social acceptability and the perception of it as a normal activity, thereby promoting quitting and preventing initiation . Research indicates that interventions aimed at reducing tobacco use are more successful if they change what is considered socially ‘normal’ behavior within the targeted community. Many factors influence the normality of smoking, both positively and negatively. Smoking can be made to seem more normal due to advertisements and efforts by the tobacco industry, which spent $9 billion on advertising in 2014, largely aimed at ethnic minorities . Of importance to the current study, smoking can also be denormalized by intelligent indoor and outdoor smokefree space policies. These policies reduce smoking in the public view, and have been shown to deter smoking and increase the perception of smoking as socially unacceptable [20, 21].
One important area of intervention is tobacco use by children, when lifetime use and addiction is typically established . Smokefree space policies protecting places frequented by children are also important for reducing exposure to SHS. Almost half of children worldwide are regularly exposed to SHS in public spaces . Extensive research has found smokefree space policies to be effective in reducing tobacco smoking and increasing cessation, while improving population health and air quality . In California, smoking bans in homes and perceptions of local smokefree outdoor areas were both found to decrease smoking and increase quit attempts . Across the USA, smokefree indoor policy bans were also found to explain smoking prevalence at the state level . In Ontario, exposure to smoking in restaurants and bar patios was found to decrease the likelihood of a quit attempt . Jurisdictions in North America are increasingly adopting legislation for smokefree public spaces; a study in Canada found that indoor smoking restrictions follow a spatial diffusion pattern, with jurisdictions following examples set by nearby and similar jurisdictions .
While indoor smoking bans have been widely enacted since 1975 in the United States , outdoor smokefree policies are less common. Despite the compilation of a national database on both indoor and outdoor smokefree space policies in the United States  analysis of these important interventions remains limited. We found few existing national studies in the USA on regional differences in smokefree space policies, or on ethnic, socioeconomic, and educational differences in the populations covered by these policies. Studies have been conducted at the state level (e.g. California ), or have been limited to parks and beaches [31, 32]. In the latter research, the odds of having a local smokefree parks policy were found to increase with higher percentages of Hispanics, people under the age of 18, Democrats, and recent movers; and to decrease with a higher percentage of older voters, smokers, and non-Hispanic Whites . Additionally, lower odds of having a smokefree space policy at the state level was significantly associated with higher percentages of smokers, and rural counties were found to be less likely to have policy protection than urban counties. Using policy data enacted up to 2009, Gonzales et al. found ethnic differences in coverage by indoor smokefree policies in the USA, with Hispanics and Asians having more coverage than Blacks .
Our research investigated inequalities in coverage by ethnicity, socioeconomic status, educational attainment, and region, for smokefree space policies covering school grounds, playgrounds, the indoors of restaurants and workplaces, and “indoor public spaces generally”. The research questions were: 1) Are there differences in the proportion of the population covered by smokefree space policies by ethnicity, income, or education?; 2) Are there differences by ethnicity in the proportion of children covered by smokefree space policies for spaces often frequented by children (restaurants, school grounds, playgrounds, and indoor “public spaces generally”)?; 3) Are there regional differences or geographic patterns in the proportion of the population covered by smokefree space policies?; and 4) What is the association between the existence of smokefree space policies covering all indoor public spaces and area-level ethnic heterogeneity, income, educational attainment, percentage white, and region?