Original ResearchClosing the knowledge gap in secondhand smoke exposure among children: employment of a five-minute household survey in China
Introduction
Secondhand smoke (SHS) has a high concentration of poisonous chemicals and a smaller median particle size than mainstream smoke.1 Extensive research has established the harmful effects of SHS.2 It places adults and children at increased risk of premature death and other adverse health outcomes, including cardiovascular and respiratory diseases.3 Children are particularly susceptible to the negative consequences of SHS. Children raised in homes with smokers, particularly pre-school age children, are at higher risk of various diseases than children who do not live with smokers.4, 5 There is, moreover, a clear dose–response effect: the health risk to the child increases with the number of smokers in the home.6, 7 There are also negative behavioural consequences: children raised in homes with smokers have a greatly increased risk of becoming regular smokers as adults than children raised in homes without smokers.8, 9, 10, 11
The majority of children's SHS exposure occurs in the home, where they spend most of their time; so SHS exposure in children is usually estimated by measuring parental smoking.5, 12 Based on the global prevalence of cigarette smoking, the World Health Organization (WHO) estimates that about one-half of all children worldwide live in homes with at least one smoker.5 But country-level estimates of SHS exposure in children are lacking, particularly in low- and middle-income countries (LMICs).
A study conducted in 31 countries found that median air nicotine concentration was 17-times higher in households with smokers compared to households without smokers and that hair nicotine concentrations in children increased with the number of smokers in the household.13 However, financial and other constraints make it infeasible to use this method to monitor changes in SHS exposure in large populations over time, particularly in under-resourced LMICs.
In most countries that ratified the WHO Framework Convention of Tobacco Control (WHOFCTC) SHS exposure in the population is monitored using the Global Adult Tobacco Survey (GATS) and the Global Youth Tobacco Survey (GYTS). Both GATS and GYTS ask respondents whether or not people smoke inside their households; GATS surveys community residents 15 years of age or older14 and GYTS surveys middle school students 13–15 years of age.15 However, children under 13 years of age do not participate in either of these widely used surveys and neither of the surveys ask respondents about the SHS exposure of their young family members. Thus these surveys do not provide information about the prevalence of SHS exposure in children under 13 years of age. Moreover, the 2010 Global Burden of Disease (GBD) estimates16 indicate that SHS is a major cause of global disability (accounting for the loss of 19.9 million disability-adjusted life-years [DALYs]), but none of the SHS-related disability occurred among individuals 5–24 years of age. This suggests methodological flaws in the GBD computation of SHS-related disability in these young age groups.
One method of obtaining information about household SHS exposure in young children is to administer a brief questionnaire about the smoking status of all household members. A previous report from the 2008 China National Rural Household Survey17 used data provided by household heads to estimate household SHS exposure in children under 18 years of age: 68% of rural children lived in households in which at least one household member had smoked at any time in the prior month. The present report uses data obtained from a more detailed household screening questionnaire to estimate the prevalence of intermittent and daily household SHS exposure in children living in a random sample of urban and rural households in one municipality in China.
Section snippets
Sampling design and procedures
The survey was conducted in Ningbo, a relatively prosperous municipality in Zhejiang Province, on the east coast of China. At the time of the survey in 2010, there were 2,855,000 households in the city with an average of 2.47 members in each household.18 The municipality includes two inner-city districts with 9% of the total population, five suburban districts with 54% of the population, and four rural counties with 37% of the population. About one-third of the population are migrants from
Results
The basic characteristics of the 1120 households that completed the survey are shown in Table 1. These households had a total of 3073 residents, including 1318 adult males (i.e., ≥18 years of age), 1318 adult females, 228 male children (i.e., <18 years of age) and 209 female children. After adjusting for study design, the prevalence of cigarette smoking was 51.5% among adult males and 0.8% among adult females; the prevalence of daily smoking was 42.8% among adult males and 0.7% among adult
Discussion
To curb the global epidemic of tobacco-associated diseases and protect those vulnerable, the implementation and effectiveness of SHS control policies need to be carefully monitored at both local and national levels.19 The method used in this study is an easy-to-use short questionnaire which can be included with any type of community survey and can be re-administered at regular intervals to monitor changes in the prevalence of household SHS exposure over time. It has the unique advantage of
Acknowledgements
This paper is a secondary analysis of a study conducted by staff at the Shanghai Mental Health Centre, the Ningbo Centre of Disease Control, and the Global Health Institute at Emory University. The paper is based on the MPH thesis project of the first author (WX) at the Rollins School of Public Health, Emory University. Mohammed K Ali, her thesis advisor, assisted in the preparation of the thesis.
Ethical approval
The study was approved by the Ethics Committee of the Shanghai Mental Health Centre and the data
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