Tobacco Exposure in Children Who Live in Multiunit Housing

Tobacco-smoke exposure causes illness in children, including asthma and respiratory infections, and has been associated with Tobacco Exposure in Childrensudden infant death syndrome, metabolic syndrome, and otitis media. There is no safe level of exposure to tobacco smoke. Very low levels of tobaccosmoke exposure have been associated with attenuated endothelial function in children, as well as decreased scores on reading, math, and block-design tests of cognitive function. Morbidity has been documented in those with the lowest levels of cotinine (0.015– 0.5 ng/ mL), and these children have greater rates of conduct disorder. Even brief exposure to ambient tobacco smoke can decrease lung function and cause persistent elevations in inflammatory cytokines.

Parental smoking is the most common source of secondhand tobacco-smoke exposure for children.Tobacco smoke can migrate through walls, ductwork, windows, and ventilation systems of multiunit dwellings and potentially affect residents in other units far removed from the smoking area. In addition to the dissemination of this secondhand smoke into other apartments, tobacco toxins may persist on and be absorbed from surfaces in the indoor environment well beyond the period of active smoking. This “thirdhand smoke” may re-emit deposited volatile compounds and particulate matter on indoor surfaces, and particulate matter in dust may be resuspended into the air as respirable suspended particulate matter. In addition to inhalation, there are other potential exposure routes, such as ingestion, that are particularly likely in children.

Recent public health efforts to reduce tobacco smoke exposure have concentrated on banning smoking in public places outside of the home, including workplaces, restaurants, and bars, leading to improved air quality in those locations. However, in New York City, where the prevalence of cigarette smoking is lower than the national average and there are strict smoking bans in bars and restaurants, a recent study found that the prevalence of elevated cotinine levels among nonsmoking adults was higher than the national average. The authors speculated that contamination of multiunit buildings with tobacco smoke from other units may contribute to these surprisingly high cotinine levels, although no direct measurement of nicotine in the air was performed. Some municipalities have proposed legislation to reduce or ban smoking in apartment buildings, and some publichousing authorities have implemented smoke-free policies. In 2009, the Department of Housing and Urban Development encouraged public-housing authorities to ban smoking in lowincome multiunit housing. There also have been reports of privately owned housing units that have banned smoking because of the potential health risks, increased costs associated with removing tobacco residue from apartments after smoking tenants leave, and the need to relocate tenants disturbed by neighbors who smoke. A recent study of low-income apartments in Boston found that 94% had detectable air nicotine levels, including 89% of apartments inhabited by nonsmokers.

There still is a lack of scientific evidence about whether smoking in multiunit housing accounts for the presence of tobacco-smoke biomarkers in children who live in a home with no adult smokers. In the current study, we used data from the 2001–2006 National Health and Nutrition Examination Survey (NHANES) to examine the association between types of housing and cotinine levels in children. We hypothesized that children who live in apartments have a higher cotinine level than children who live in detached homes and that this relationship persists when controlling for poverty and race/ethnicity.

The majority of US children who live in homes where no one smokes inside have biochemical evidence of tobaccosmoke exposure, and cotinine levels are significantly higher in children who live in apartments, compared with those who live in detached houses. Although it is likely that some of this excess exposure is from family members who smoke only outside of the home but carry in tobacco residue on their clothes, this is unlikely to explain all of the discrepancy. In addition, our data are consistent with the findings from Kraev et al, which showed that 89% of low-income apartments with no smokers had detectable air nicotine concentrations.

The finding that children are at risk for tobacco-smoke exposure in apartments may accelerate the current trend of limiting smoking in multiunit housing. One of the public health benefits seen from the restriction of smoking in the workplace has been a reduction in smoking rates and number of cigarettes smoked. Restrictions in multiunit housing may have a similar effect on residents; however, implementing these restrictions without providing smoking-cessation assistance for residents also might create a significant burden for low-income smokers. Adult residents of Department of Housing and Urban Development– funded housing who are uninsured will need access to free cessation programs, such as those offered by the national network of quitlines.

Banning smoking in multiunit dwellings by property owners or by regulation would be the obvious way to mitigate contamination and children’s exposure to tobacco toxins. Concern has been raised that dictating what can be done in a private dwelling is an infringement on personal privacy and liberty; however, this argument holds only if smoking in an adjacent apartment has no impact on one’s neighbors. Legal doctrine supports restrictions on private behavior if there are consequences for others, such as noise levels, noxious odors, or release of toxic chemicals. Tobacco smoke can be categorized both as a noxious odor and a toxic chemical. In addition, there is a strong probability that exposure may result in physical harm, particularly for children with underlying illnesses such as asthma. A recent analysis addressing smoke-free public housing argued that phasing in such a policy as new leases were signed and existing ones renewed would be justified on legal and social justice grounds. The association between living in an apartment and child cotinine levels provides additional support to this exposure-reduction strategy. Smoke-free policies should recognize that tobacco smoke drifts and can be measured in high quantities more than 20 feet from an outdoor source. Because restriction inside apartments may encourage increased smoking in common areas where exposure to nonsmokers still may occur, these policies should include smoking restrictions for balconies, common porch areas, and entrances. Our overall prevalence of children exposed to tobacco smoke is significantly higher than that reported in the 2006 Surgeon General’s report. This difference is most likely because the NHANES now uses high-sensitivity cotinine testing that allows the detection of low levels of smoke exposure. Identifying those at risk for these low levels of exposure is important because there is increasing evidence that even small or brief exposure to tobacco smoke can cause physiologically significant cardiovascular effects. Lowlevel exposure to tobacco smoke also has been associated with lower scores on cognitive testing.

Although there was a significant association between living in an apartment and cotinine levels for white and black children, this was not the case for those of Hispanic ethnicity or other races. Overall, Hispanic and Asian adults have much lower smoking rates (13.3% and 9.6%, respectively) than black (19.8%) or white (21.4%) adults. This difference particularly is striking for women (8.3% of Hispanic and 4.0% of Asian women smoke compared with 15.8% of black women and 19.8% of white women). Because Hispanic and Asian immigrants are more likely to be found in high-density ethnic enclaves where multiunit housing is common, it is possible that the lower smoking prevalence among some ethnic groups reduces the overall tobacco-smoke burden in some multiunit housing. There are other potential sources of exposure that need to be considered. Potential sources may include daycare centers or child-care arrangements as well as smoke residue from a parent or caregiver who smokes outside. Other studies have found significantly increased house dust and air nicotine levels in households with a mother who smokes outside, with corresponding increases in children’s urine cotinine level. There also is an increase in air and surface nicotine found in used cars previously owned by smokers. This is an important issue for families who may believe that they are protecting their children by smoking outside. However, because smoking prevalence is much lower than exposure prevalence, this does not explain all of the excess exposure.

There are limitations to these data. First, we only were able to examine the association between apartment living and tobacco-smoke exposure; there are other unmeasured potential confounders. Population density and current smoke-free housing legislation are 2 factors that likely play a role; these will need to be examined in future research. In addition, the NHANES data set has no information about home smoking bans or outside smoking behavior, so we cannot know how many of these children have parents who smoke outside or if they are exposed at daycare centers or relatives’ homes. We hope that future research will be able to separate out the individual contributions of apartment smoke drift, outside-smoker “off-gassing” and thirdhand smoke, occasional inside smoking by visitors, or exposures outside of the home.

Finally, people who smoke may inaccurately report whether they smoke anywhere inside the home. If underreporting rates varied between those in apartments versus single-family homes, our results may be biased. Assuming no differential in inaccurate reporting, children in apartments also might be expected to have higher cotinine levels because of the smaller square footage in apartments versus single-family homes. In general, however, people who smoke have demonstrated low rates of underreporting smoking behaviors in nonintervention trials. Finally, a growing number of buildings are smoke-free already, leading to an underestimation of the exposure rate in multiunit dwellings where smoking still is allowed.

Most children in the US continue to be exposed to tobacco smoke, even with the growing knowledge of its damaging effects at low levels of exposure. It is vital to understand the contribution of all potential sources of exposure for children: parents smoking outside, daycare, visiting homes where smoking is allowed, and from connected dwellings. However, significant tobacco-smoke contamination in the air of nonsmoking units of multiunit housing already has been shown. This study is the first to document through human biological sampling that disseminated tobacco smoke from multiunit apartments may contribute to the actual exposure of children. In addition, there are likely to be many adult nonsmokers who also are exposed to tobacco smoke by this mechanism. Biochemical data demonstrating the increased risk of involuntary tobacco-smoke exposure posed by living in apartments may change public opinion and policies about smoke-free multiunit housing for those who live in low-income housing, and for those who live in apartments owned by private companies. These results provide direct evidence for a background level of tobacco-smoke contamination in multiunit housing at levels associated with childhood morbidity. Ultimately, smoke-free multiunit housing could improve health status by reducing nonsmokers’ exposure to tobacco smoke in their own units.

AUTHORS: Karen M. Wilson, MD, MPH,a,b Jonathan D.Klein, MD, MPH,a,b Aaron K. Blumkin, MS,a Mark Gottlieb, JD,b,c and Jonathan P. Winickoff

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