Article Text

Trends in home smoking bans in the USA, 1995–2007: prevalence, discrepancies and disparities
1. Xiao Zhang1,
2. Ana P Martinez-Donate1,2,
3. Daphne Kuo3,
4. Nathan R Jones2,
5. Karen A Palmersheim4
1. 1Department of Population Health Sciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
4. 4Center for Urban Initiatives and Research, University of Wisconsin–Milwaukee, Milwaukee, Wisconsin, USA
1. Correspondence to Professor Ana P Martinez-Donate, Assistant Professor, Department of Population Health Sciences, Carbone Cancer Center, University of Wisconsin–Madison, 610 Walnut St., 605 WARF, Madison, WI 53726-2397, USA; martinezdona{at}wisc.edu

## Abstract

Background Home smoking bans significantly reduce the likelihood of secondhand smoke exposure among children and non-smoking adults. The purpose of this study was to examine national trends in (1) the adoption of home smoking bans, (2) discrepancies in parental smoking ban reports and (3) household and parental correlates of home smoking bans among households with underage children from 1995 to 2007.

Methods The authors used data from the 1995–1996, 1998–1999, 2001–2002, 2003 and 2006–2007 Tobacco Use Supplement of the US Current Population Survey to estimate prevalence rates and logistic regression models of parental smoking ban reports by survey period.

Results Overall, the prevalence of a complete home smoking bans increased from 58.1% to 83.8% (p<0.01), while discrepancies in parental reports decreased from 12.5% to 4.6% (p<0.01) from 1995 to 2007. Households with single parent, low income, one or two current smokers, parents with less than a college education or without infants were consistently less likely to report a home smoking ban over this period (p<0.05).

Conclusions Despite general improvements in the adoption of home smoking bans and a reduction on parental discrepancies, disparities in the level of protection from secondhand smoke have persisted over time. Children living in households with single parents, low income, current smoker parents, less educated parents or without infants are less likely to be protected by a home smoking ban. These groups are in need of interventions promoting the adoption of home smoking bans to reduce disparities in tobacco-related diseases.

• Home smoking bans
• trends
• health disparities
• secondhand smoke
• environmental tobacco smoke
• prevalence

## Introduction

Children exposed to secondhand smoke (SHS) are at an increased risk for sudden infant death syndrome, acute respiratory infections, recurring ear problems and more severe asthma.1 The home is a primary location of SHS exposure for children.1 2 Recently, attention has been drawn to a new proposed mode of involuntary exposure to tobacco constituents—thirdhand smoke (THS), which refers to residual tobacco smoke contamination that remains after the cigarettes is extinguished.3 Children are especially susceptible to THS exposure because they breathe near, crawl and play on, touch and mouth contaminated surfaces.3 The adoption of a home smoking ban can significantly reduce the level of SHS and THS exposure. A home smoking ban refers to rules set up by household residents or other individuals to restrict or ban cigarette smoking inside the home.4 Previous research has found an association between home smoking bans and a reduction in toddlers' mean urinary cotinine levels, an indicator of exposure to smoke.5 Studies also suggest that household smoking rules convey an anti-tobacco social norm that help deter adolescents from smoking regardless of their parents or friends' smoking behaviour.6–9

In the USA, survey results indicate that the prevalence of home smoking bans has increased.10 11 By 2008, the percentage of smoke-free homes ranged from 68.8% to 85.7% depending on the state.12 However, the national trend has not been systematically examined for households with underage children, a population particularly vulnerable to the effects of SHS exposure.

Previous research indicates that smoking bans are associated with a number of individual and household characteristics, including race/ethnicity, presence and age of children, smoking status of household residents, educational attainment, household income and smoking status of friends.4 13–17 In general, home smoking bans are more frequently reported by individuals with higher education levels, higher income, with infants in the households and with non-smoking friends. African–Americans were less likely to report a home smoking ban compared with the white population. However, the relationship between other household characteristics and a complete smoking ban remains understudied. For example, literature has consistently shown that children in single-parent households have worse physical and mental outcomes than those in two-parent households.18 19 Little is known regarding whether the household structure, that is, nuclear family, paternal or maternal mono-parental households, may be related to likelihood of having a home smoking ban. There is also limited knowledge regarding possible changes in disparities on rates of home smoking bans by demographic and socioeconomic factors over time.

Analyses of home smoking bans have relied largely on the responses of one household member. Relatively few studies have investigated the discrepancies in perceptions among different household members. Children living in households where adults offer inconsistent reports about the home smoking ban may be at higher risk of SHS exposure than their counterparts in homes where both parents report the existence of a complete home smoking ban. The inconsistent report would suggest either a smoking ban has not really been adopted by all members of the households or the adopted smoking ban is not strongly enforced. Mumford et al20 used 1998–1999 Tobacco Use Supplement (TUS) to the Current Population Survey(CPS) and found that, nationally, an estimated 12% of households with two or more adults provided inconsistent reports about home smoking bans. Discrepancies varied by smoking status, socioeconomic status, race/ethnicity and presence of children. However, as overall rates of home smoking bans have increased and social recognition of the harm of SHS exposure, especially to children, has greatly improved over the last decade throughout the USA,21 the discrepancy rate may have changed. To date, we are unaware of any study examining this question. Yet, it has important implications for both research and public health policy.

The current study used data from the Tobacco Use Supplement of the Current Population Survey (TUS-CPS), a nationally representative survey. The data provided comparable measures to track national trends in the prevalence of home smoking bans in households with underage children from 1995 to 2007 as well as the evolution of parental discrepancies in the reporting of home smoking bans among two-parent households from 1995 to 2007. We investigated national trends in home smoking bans, household and parental characteristics associated with the establishment of home bans, and discrepant parental reports over this period.

## Methods

### Study population

We used data from the 1995–1996, 1998–1999, 2001–2002, 2003 and 2006–2007 TUS-CPS. The TUS-CPS is a survey of tobacco use administered as a supplement to the CPS. The TUS-CPS uses a sample of households and is designed to represent the civilian non-institutionalised population of the USA. All permanent household members aged 15 years or older are eligible for the interview. The TUS-CPS provides data on a nationally representative sample of about 240 000 individuals within a given survey period. For the five yearly survey periods, the TUS-CPS response rate, including both self- and proxy responses, were 84.5%, 83.5%, 75.0%, 75.2% and 73.7%, respectively.

In the current study, because the analysis focused on home smoking rules, the analytical unit was the household. Only primary family households with underage children (<18 years old) were included in our analysis. We further divided the sample into two groups: two-parent households and single-parent households. A parent refers to a household's reference person or his/her spouse or partner and they did not need to be the child/children's biological parent. The no-smoking home bans were reported by one or both parents in two-parent households and by the single parent in single-parent households. Households were excluded from analyses if no response on home bans status from either the reference person or the spouse or partner was gathered. No proxy responses were collected on home smoking ban status.

### Measures

#### Home smoking bans

All TUS survey respondents were asked a question about the smoking rules in their home. Based on evidence demonstrating the limited effectiveness of partial smoking bans in the household,22 23 we classified respondents' answers into two categories: a complete smoking ban report (ie, ‘No one is allowed to smoke anywhere INSIDE YOUR HOME’) versus a partial or no smoking ban report (ie, ‘Smoking is allowed in some places or at some times INSIDE YOUR HOME’ or ‘Smoking is permitted anywhere INSIDE YOUR HOME’).

A household with a complete home smoking ban is a single-parent household in which the parent reported a complete ban or a two-parent household in which at least one parent reported a complete ban. Because there are households in the sample in which two parents/partners provided discrepant reports about home smoking bans, we classified two-parent households into two further categories: households in which spouses/partners provided discrepant responses on the existence of a complete home smoking ban and households where neither of the spouses/partners reported a complete home smoking ban. Analyses on discrepant reports included only two-parent households in which both parents answered to the question on home smoking ban status.

#### Individual and household variables

The following factors potentially associated with the establishment of a non-smoking rule in the home were analysed: household structure, highest parental education level, age of the youngest child, annual household income, parental race/ethnicity, parental age and parental smoking status. The specific categories considered are shown in tables 1 and 2. Smoking status was assessed for each parent residing in the households. Based on parental smoking status, households were categorised into four groups: households where both parents are current smokers (he/she has smoked more than 100 cigarettes in their lifetime and currently smokes some days or every day), households with only one current smoker, households with no current smokers but where one or both parents were former smokers (he/she has smoked more than 100 cigarettes in their lifetime but does not currently smoke) and households with neither current nor former smokers.

Table 1

Sociodemographic factors associated with establishment of a complete smoking home ban* among two-parent households (1995–2007)

Table 2

Sociodemographic factors associated with establishment of a complete smoking home ban* among single-parent households (1995–2007)

### Statistical analysis

Survey and household weights provided by the TUS-CPS were used to account for the complex sampling design and clustering to produce population estimates. We calculated simple descriptive statistics on the prevalence of a complete smoking ban over different survey periods. We then conducted multivariate logistic regressions to examine (1) associations between sociodemographic and household-level variables and the establishment of a complete smoking ban by study period and (2) significant changes in prevalence from one survey period to the next. These analyses were stratified by household structure, that is, two-parent versus single-parent households.

ORs and 95% CIs estimated with the regression models described above were compared across survey periods to investigate whether there were significant changes in the relationships between each factor and home smoking ban status. Non-overlapping 95% CIs were considered significant at the 95% level. All analyses were performed with the software STATA/SE V.10.0 (StataCorp LP).

## Results

### Overall trends in home smoking bans

The overall prevalence of a complete home smoking ban in all household significantly increased from 58.1% of households in 1995–1996 to 67.0% in 1998–1999, 72.8% in 2001–2002, 79.4% in 2003 and 83.8% in 2006–2007, with this increase being statistically significant for each study period compared with its previous one (p<0.01) after adjusting for individual and household characteristics.

### Trends in home smoking bans among two-parent households

As shown in table 1, the overall prevalence of a complete home smoking ban within two-parent households (reflecting the percentage of households where at least one of the two parents reported the existence of a smoking ban; see below for analysis of discrepancies) has significantly increased from 62.6% in 1995–1996 to 87.7% in 2006–2007, with this increase being statistically significant for each study period compared with the previous one (p<0.05). The increase was observed regardless of parental educational level, age of youngest child, annual household income, parental race/ethnicity, parental smoking status or parental ages. However, disparities in the distribution of home smoking bans persisted over time.

After adjusting for household- and individual-level confounding factors, reports regarding the existence of a complete home smoking among two parents households varied by highest parental education, age of youngest child, household income, parental race/ethnicity composition, parental smoking status and parental ages. Highest parental education level was positively associated with the reporting of a complete home smoking ban. In contrast, age of youngest child was negatively associated with the likelihood of having a smoking ban. Annual household income and parental smoking status were found to be strong predictors of the existence of a complete home ban. Households with higher income were consistently more likely to adopt a complete home ban than those with lower income, and this disparity seems to have increased over time as the adjusted OR value for households with an annual income of at least US$50 000 versus households reporting an annual income of <US$25 000 grew from 1.32 in 1995–1995 to 2.02 in 2006–2007 (p<0.05). Regarding parental smoking status, in general, a gradient was observed indicating that households comprising only never-smoker parents were most likely to have a complete ban, followed by those with no current but one or two former smoker(s) and then followed by households with one current smoker. Households with two current smoker parents were least likely to have a ban.

Households in which parents were Hispanic or white and Hispanic were consistently found to have greater odds of reporting a complete home smoking ban than those with white-only parents over the survey periods. At the same time, households in which both parents' age fell in the range of 18–29 were generally more likely to report a home smoking ban than other age combinations, particularly since 2003. Among two-parent households, in addition, the female parents were consistently less likely to report a complete home ban than their male partners after adjusting for demographic and socioeconomic factors. The OR value was 0.84 in 1995–1996, 0.84 in 1998–1999, 0.85 in 2001–2001, 0.82 in 2003 and 0.80 in 2006–2007 (p<0.05).

### Trends in home smoking bans among single-parent households

An increasing prevalence of complete home smoking bans among single-parent households was also observed. The rates increased from 45.7% to 74.6%; the increase was statistically significant for every survey period compared with the previous one (p<0.05; table 2). The gender of the parent (ie, single-mother versus single-father household) did not affect the odds of having a home smoking ban. The associations between other parental and household characteristics and the establishment of a home smoking ban were similar to those found for two-parent households.

### Household structure and home smoking bans

In general, throughout all survey periods, single-parent households were consistently much less likely (p<0.01) than two-parent households to report a complete home smoking. The OR was 0.52 in 1995–1996, 0.54 in 1998–1999, 0.60 in 2001–2001, 0.57 in 2003 and 0.58 in 2006–2007.

### Discrepancies in parental reports among two-parent households

Our previous estimates for two-parent households reflected the percentage of households where at least one of the two parents reported the existence of a smoking ban in the home. However, our analyses revealed that two parents' reports were not always consistent with each other and the percentage of discrepant reports in two-parent households changed over time. Specifically, as shown in figure 1, the percentage of households in which both parents agreed on the existence of a complete home smoking ban increased from 53.8% during 1995–1996 to 85.2% during 2006–2007. Accordingly, the percentage of households in which the two parents gave discrepant reported on a complete home smoking ban significantly decreased from 12.5% to 4.5% over time (p<0.001). In addition, the prevalence of households that lacked a complete home smoking ban according to both parents significantly decreased from 33.7% during 1995–1995 to 10.3% during 2006–2007 (p<0.001).

Figure 1

Trends in parental responses regarding the existence of a home smoking ban among two-parent households (two-parent households included those in which both of the parents gave valid responses), USA, 1995–2007 responses.

## Discussions

This study examined national trends in home smoking bans, individual- and household-level factors associated with the adoption of a complete home smoking ban, and parental discrepancies in the reporting of home smoking bans among households with underage children from 1995 to 2007.

Our findings reveal that even though the prevalence of a complete home smoking ban among households with underage children has risen over time, approximately 16% of households did not have any restrictions against smoking by 2006–2007 and children in these households were still potentially exposed to the harm of SHS exposure.

Furthermore, this study identified persisting disparities in the rate of adoption of a home smoking ban. Family structure, parental education, age of the youngest child, household income, race/ethnic composition and smoking status emerged as factors significantly associated with the likelihood of having adopted a home smoking ban. Children living in single-parent households or with less educated parents were less likely to be protected by a complete smoking ban than their peers living in two-parent households or with more educated parents. This is particularly problematic considering previous research has found that single parents and less educated parents are more likely to smoke than married and more educated parents.24 25 Households with infants were most likely to restrict smoking in the home. This may reflect that parents underestimate the harms of SHS exposure among older children and calls for interventions to increase awareness regarding SHS exposure among parents of older children. The disparity between households with higher and lower socioeconomic status persisted and even widened over time, pointing at the need to target low-income families to promote their use of home smoking bans and increase the protection of all children living in these households. Households with at least one Hispanic parent were more likely to establish a complete home ban than other race/ethnicity combinations. This result is consistent with previous research on Hispanic populations suggesting higher prevalence of home smoking bans among this population compared with other ethnic and racial groups.2

Consistent with results from previous studies, parental smoking status was the largest single factor associated with the odds of having a smoking ban in the home.14–16 Households with two current smoker parents were 25 times less likely to have a complete home smoking ban compared with those with only never-smoker(s). However, it is reassuring to find that the prevalence of a complete ban within households with two current smokers has increased greatly from 14.1% in 1995–1996 to 44.2% in 2006–2007. A similar trend was observed by Pizacani et al26 in a longitudinal study in Oregon indicating a 32% increase in complete bans over 21 months for households with at least one smoker. Still the gap by parental smoking status persisted over time, and this has important implications for future interventions. First, it indicates that children who are at highest risk for SHS exposure in the home, that is, those living in households with current or former smokers, are indeed less likely to be protected by a home smoking ban. Second, it underscores the need to focus on families with one or two parents who smoke to promote their adoption of home smoking bans. Finally, it suggests that one of the most direct and effective ways to reduce the risk of SHS exposure in the households would be to promote smoking cessation. Jarvis et al27 examined the impact of smoke-free homes on children's exposure to SHS, which was validated by cotinine measures, and they found that living in a smoke-free home offers children a considerable, but not complete, degree of protection against exposure to parental smoking. Interestingly, younger parents in two-parent households seemed to be more likely to establish a complete home ban to ensure smoke free. This may suggest that the younger generations are more aware of the harm associated with exposure to SHS and THS.

In order for a home smoking ban to be effective, it is important that both parents within the household are in agreement. Discrepant reports between parents may reflect lax enforcement of the non-smoking rule to the point that one of the parents does not recognise the existence of such rule. Analyses concerning discrepancy/consistency reports among two-parent households regarding the existence and degree of a home smoking ban showed that the percentage of households in which both parents agreed on the existence of a complete home smoking ban kept rising, while the percentage of households in which neither parent reported a complete home ban or households in which discrepant reports were provided shrunk over time. In particular, the extent of discrepant reports was over 10% before 2000 and then it decreased significantly to below 5% in 2003 and 2006–2007. A reduction in the rates of discrepant parental reports regarding home smoking ban status along with an overall increase in the prevalence of home smoking bans during this 10-year period represents important progress towards reduction of SHS and THS exposure.

The trend observed in the level of parental concordance on home smoking ban reports has also important implications for research methodology. The results suggest that previous studies using home smoking ban data from before 2005 and based on individual reports may yield inaccurate estimates of the prevalence of these rules. Thus, researchers who use early data sources should take into account responses from more than one household member if they are available instead of relying on the answers from one individual household member. Based on the trend observed, this may be less of a problem for more recent and, presumably, future studies. Hence, in the context of limited resources, surveying only one parent in a two-parent household, particularly in households with no parental smoking, may be a more cost-effective way to get crude estimates on the use of home smoking bans.

### Limitations

There are several limitations to our study. These limitations also suggest possible future research directions. First, there were minor changes in the wording of the TUS-CPS home smoking ban question after 2002. The 2003 and 2006 version of the question replaced ‘in your home’ with ‘inside your home’. In addition, the new version also added an explanation of the meaning of word ‘rule’ (ie, ‘rules’ include any unwritten ‘rules’ and pertain to all people whether or not they reside in the home or are visitors, workmen, etc'). Conceivably, most people would interpret ‘in your home’ and ‘inside your home’ as equivalent expressions. Yet when ‘rules’ not only apply to home residents but also visitors and workmen, it is possible that respondents to the new version of the question would underestimate the existence of a home ban compared with the old question. By comparison, this suggests that respondents to the old wording of the question, prior to 2003, may have overstated in their reports of complete home smoking bans (eg, if household residents were not allowed to smoke but visitors or workers were not held to the same rule). This suggests that actual prevalence of a complete home smoking bans for the periods before 2003 may be lower than our estimates suggest, even though the likelihood that households that actively ban in-home smoking among residents are going to be comfortable with allowing visitors to smoke is small. The CPS also recoded its race/ethnicity question. Starting in 2003, respondents were able to select more than one race. This change may affect our estimates regarding the association between race/ethnicity and home smoking ban reports.

Second, a subset of the 2001–2002 TUS-CPS sample was followed longitudinally and re-interviewed in 2003 round. The increase in the prevalence of a complete home smoking ban between 2001–2002 and 2003 was more marked than that between other survey periods. This may reflect repeated testing bias. Hence, the results for that survey period may overestimate true prevalence rates of home smoking bans among the US population.

Third, all data are based on self-report. As awareness regarding the risks associated with SHS exposure have become more widely known over time, parents' responses on home smoking bans may have be more affected by social desirability. Thus, to prevent information bias, future research on home smoking bans should include objective measures as well, for example, air quality detection.

In conclusion, the results presented in this study indicate that the overall prevalence of a complete home smoking ban within households with resident children under the age of 18 has increased from 1995 to 2007 in the USA, regardless of various socio-demographic or household characteristics. The results also underscored that disparities on the adoption of an effective measure to reduce child exposure to SHS and THS persisted. Thus, it is important to focus tobacco control and prevention efforts on the factors that may impede the establishment of a complete home smoking ban among particular population groups. Children living in households with single parents, low income, parents who are current smokers, less educated parents or without infants are less likely to be protected by a home smoking ban. These groups need to be targeted by future interventions in order to continue reducing SHS exposure among the US population as a whole and also to reduce disparities in tobacco-related diseases.

• This paper shows that the prevalence of the adoption of a home smoking ban among households with underage children increased steadily in the US from 1995 to 2007, while discrepancies in parental reports of a smoking ban decreased.

• Households with single parents, low income, one or two current smokers, parents with less than a college education, or without infants were consistently less likely to report a home smoking ban over this period.

## Footnotes

• Funding This study was supported by grant #5 P50 CA143188, NIH/National Cancer Institute Training Tobacco Scientists (TTS) Mini Grant (XZ, PI) from University of Wisconsin Center For Tobacco Research and Intervention.

• Competing interests None.

• Provenance and peer review Not commissioned; externally peer reviewed.

## Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.